MLPAO MLA/T Certification Exam — Questions and Answers

Question 1: What is the principle of the thrombin time (TT) test?

Measures the activity of Factor VIII
Measures platelet adhesion to collagen
Measures the time for plasma to clot after adding thrombin directly (Correct answer)
Measures the time for plasma to clot after adding tissue factor

Correct answer: Measures the time for plasma to clot after adding thrombin directly

The thrombin time measures the time for fibrin clot formation after adding exogenous thrombin directly to citrated plasma, bypassing the intrinsic and extrinsic pathways. It evaluates the final step of coagulation (fibrinogen to fibrin conversion) and is prolonged by heparin, low fibrinogen, dysfibrinogenemia, and elevated FDPs.

Question 2: What is the India ink preparation used to detect?

Acid-fast bacilli
Plasmodium species
Gram-negative diplococci
Cryptococcus neoformans capsule in CSF (Correct answer)

Correct answer: Cryptococcus neoformans capsule in CSF

The India ink preparation is a negative staining technique that reveals the thick polysaccharide capsule of Cryptococcus neoformans in CSF. The ink particles are excluded by the capsule, creating a clear halo around the yeast cell against a dark background. The cryptococcal antigen test (CrAg) has largely replaced India ink due to higher sensitivity.

Question 3: A patient taking unfractionated heparin develops a platelet drop from 250 to 100 × 10⁹/L on day 7 with a new DVT. The 4T score is 7. What is the next step?

Transfuse platelets
Continue heparin and monitor
Switch to low-molecular-weight heparin
Immediately stop all heparin, start alternative anticoagulant, and send HIT antibody testing (Correct answer)

Correct answer: Immediately stop all heparin, start alternative anticoagulant, and send HIT antibody testing

A high 4T score (6-8) with >50% platelet drop, timing on day 7, and new thrombosis strongly suggests HIT type II. All heparin must be stopped immediately (including flushes), an alternative non-heparin anticoagulant started (argatroban or fondaparinux), and HIT antibody testing sent. LMWH cross-reacts with HIT antibodies and is contraindicated.

Question 4: Which serological test is used for the diagnosis of syphilis and what is the screening algorithm used in Canada?

Dark-field microscopy for all stages
RPR only; no confirmation needed
Reverse algorithm: treponemal test (EIA/CIA) screen followed by RPR and confirmatory treponemal test (Correct answer)
FTA-ABS as the sole test

Correct answer: Reverse algorithm: treponemal test (EIA/CIA) screen followed by RPR and confirmatory treponemal test

Many Canadian laboratories use the reverse syphilis screening algorithm: a treponemal-specific immunoassay (EIA or CIA) is used for screening, followed by RPR (a non-treponemal test to assess disease activity) and a second treponemal test (TP-PA or FTA-ABS) for confirmation. This approach has higher sensitivity for detecting latent syphilis.

Question 5: A throat culture grows beta-hemolytic colonies. What additional testing should be performed?

Oxidase test
Bile esculin test
Bacitracin susceptibility or PYR test to presumptively identify Group A Streptococcus (Correct answer)
Coagulase test

Correct answer: Bacitracin susceptibility or PYR test to presumptively identify Group A Streptococcus

Beta-hemolytic colonies from throat culture should be tested with bacitracin (Group A Strep is susceptible, most other groups are resistant) or PYR test (Group A Strep is positive) for presumptive identification. Serological Lancefield grouping (latex agglutination) provides definitive group identification. Group A Strep is the primary throat pathogen requiring treatment.

Question 6: A physician's office sends a urine specimen for culture and sensitivity to the laboratory. Upon receipt, the MLA/T notices the specimen is in a non-sterile container. What is the most appropriate action?

Aliquot a small amount for culture and discard the rest.
Process the specimen and add a comment about the container.
Transfer the urine to a sterile container and proceed with testing.
Reject the specimen and request a new sample collected in the proper container. (Correct answer)

Correct answer: Reject the specimen and request a new sample collected in the proper container.

Microbiology specimens for culture must be collected in sterile containers to prevent the introduction of environmental bacteria, which would lead to inaccurate results. A non-sterile container compromises the specimen's integrity, making it unacceptable for culture. The proper procedure is to reject the specimen and notify the provider to collect a new, valid sample.

Question 7: What does the anion gap calculation help identify?

Hypernatremia cause
Respiratory alkalosis
Renal tubular function
Metabolic acidosis etiology (Correct answer)

Correct answer: Metabolic acidosis etiology

The anion gap helps differentiate causes of metabolic acidosis. It is calculated as Na+ - (Cl- + HCO3-), with a normal range of approximately 8-12 mmol/L. An elevated anion gap suggests accumulation of unmeasured acids such as lactate, ketoacids, or toxins.

Question 8: A body fluid from a knee joint aspiration has a WBC count of 75,000/µL with 95% neutrophils and a positive Gram stain showing gram-positive cocci in clusters. What is the diagnosis and management?

Septic arthritis requiring urgent surgical drainage and IV antibiotics (Correct answer)
Gout requiring anti-inflammatory treatment
Osteoarthritis flare
Rheumatoid arthritis

Correct answer: Septic arthritis requiring urgent surgical drainage and IV antibiotics

WBC >50,000/µL with >90% neutrophils combined with a positive Gram stain confirms septic arthritis. Gram-positive cocci in clusters suggest Staphylococcus aureus, the most common cause. This is an orthopedic emergency requiring urgent joint drainage (surgical washout or serial aspirations) and IV anti-staphylococcal antibiotics to prevent joint destruction.

Question 9: Which Westgard rule is considered a 'warning' rule rather than a rejection rule?

R-4s
1-2s (Correct answer)
1-3s
2-2s

Correct answer: 1-2s

The 1-2s rule is a warning rule that triggers inspection of additional QC data. A single QC result exceeding 2 standard deviations from the mean occurs randomly about 5% of the time and does not alone indicate an analytical problem. It prompts checking other Westgard rules for true violations.

Question 10: An MLA performs a gravimetric check on a P1000 micropipette set to dispense 1000 µL. The average mass of ten dispenses of reagent water is 0.982 g, which converts to a volume of 982 µL. This finding indicates a primary problem with the pipette's:

Ergonomics
Accuracy (Correct answer)
Tip compatibility
Precision

Correct answer: Accuracy

Accuracy is the measure of how close a dispensed volume is to the intended or set volume. Since the average volume (982 µL) is significantly different from the target volume (1000 µL), the pipette is inaccurate. Precision refers to the repeatability or closeness of the ten individual measurements to each other, which cannot be determined from the average alone.

Question 11: Which serological marker is the first to appear after hepatitis B infection and indicates active viral replication?

HBsAg (hepatitis B surface antigen) (Correct answer)
Anti-HBc IgG
HBeAg (hepatitis B e antigen)
Anti-HBs (hepatitis B surface antibody)

Correct answer: HBsAg (hepatitis B surface antigen)

HBsAg is the first serological marker to appear after HBV infection, detected before symptoms and before antibody development, indicating active hepatitis B virus infection.

Question 12: What is the purpose of an anaerobic culture and which specimen types should NOT be cultured anaerobically?

To grow fungi; blood cultures
To isolate oxygen-sensitive bacteria; specimens from sites with normal anaerobic flora (stool, vaginal) (Correct answer)
To grow aerobic organisms only; throat swabs
To isolate viruses; tissue specimens

Correct answer: To isolate oxygen-sensitive bacteria; specimens from sites with normal anaerobic flora (stool, vaginal)

Anaerobic cultures isolate bacteria that cannot survive in oxygen. Specimens from sites with normal anaerobic flora (stool, vaginal, oral) should not be cultured anaerobically because normal flora will overgrow pathogens. Appropriate specimens include normally sterile body fluids, deep tissue, and aspirates from closed abscesses.

Question 13: What is the significance of extended incubation (up to 14 days) for blood cultures from patients with suspected endocarditis?

Extended incubation only detects contaminants
Some endocarditis pathogens (HACEK group, Brucella) are slow-growing and may not be detected in standard 5-day incubation (Correct answer)
Extended incubation is for fungal detection only
Extended incubation is never needed with modern systems

Correct answer: Some endocarditis pathogens (HACEK group, Brucella) are slow-growing and may not be detected in standard 5-day incubation

HACEK organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella) and other fastidious endocarditis pathogens may require extended incubation (up to 14 days) for detection. Modern automated systems detect most pathogens within 5 days, but the microbiology laboratory should be notified of suspected endocarditis to ensure appropriate incubation.

Question 14: A fecal sample for culture and sensitivity is collected:

by septic transfer.
by aseptic technique. (Correct answer)
by clean catch.
by sterile transfer.
by antiseptic technique.

Correct answer: by aseptic technique.

A fecal sample for culture and sensitivity must be collected using aseptic technique. This involves employing procedures to prevent contamination of the sample from external sources, ensuring that only the microorganisms present in the stool are cultured. While stool is not sterile, aseptic collection minimizes the introduction of environmental contaminants that could interfere with accurate diagnostic results.

Question 15: The laboratory rejects a specimen for INR testing because the specimen is in an evacuated tube with a light blue top and the specimen is:

delayed in transit for 6 hours. (Correct answer)
separated.
spun down for 10 minutes.
refrigerated for 1 hour before being tested.
filled three-quarters full.

Correct answer: delayed in transit for 6 hours.

A specimen for INR testing, collected in a light blue top tube with sodium citrate, is typically rejected if there's a significant delay in transit, such as 6 hours. Coagulation factors are labile and can degrade over time, leading to inaccurate results if not processed or tested within recommended timeframes. Prolonged delays compromise the integrity of the coagulation factors, making the test unreliable.

Question 16: In clinical chemistry, what does the term 'hemolysis' refer to and why is it a concern?

Clotting of the sample; it reduces volume
Bacterial contamination; it degrades analytes
Lipid accumulation; it causes turbidity
Breakdown of red blood cells; it releases intracellular contents that interfere with assays (Correct answer)

Correct answer: Breakdown of red blood cells; it releases intracellular contents that interfere with assays

Hemolysis refers to the rupture of red blood cells, releasing intracellular contents such as potassium, LDH, and hemoglobin into the serum or plasma. This is the most common preanalytical error in clinical chemistry and can falsely elevate or decrease many analyte measurements.

Question 17: Which body fluid analysis is used to differentiate a transudate from an exudate?

Blood culture
Light's criteria (protein ratio, LDH ratio, and LDH level) applied to pleural fluid (Correct answer)
Complete blood count
Urine dipstick

Correct answer: Light's criteria (protein ratio, LDH ratio, and LDH level) applied to pleural fluid

Light's criteria classify pleural effusions as exudates if any one criterion is met: 1) Pleural fluid protein/serum protein >0.5, 2) Pleural fluid LDH/serum LDH >0.6, 3) Pleural fluid LDH >2/3 the upper limit of normal serum LDH. Transudates result from hydrostatic/oncotic pressure imbalance (CHF, cirrhosis), while exudates indicate infection, malignancy, or inflammation.

Question 18: Which of the following is a transfusion science test?

DAT (Correct answer)
Retic
AFP
CRP
NH4

Correct answer: DAT

The Direct Antiglobulin Test (DAT) is a crucial test in transfusion science, used to detect antibodies or complement components bound to red blood cells in vivo. It is vital for diagnosing conditions such as hemolytic disease of the newborn, autoimmune hemolytic anemia, and transfusion reactions. The other options listed are typically associated with chemistry or hematology, not directly transfusion science.

Question 19: What does proteinuria detected by dipstick primarily measure?

All proteins equally
Only Bence Jones protein
Primarily albumin (the indicator is more sensitive to albumin than other proteins) (Correct answer)
Only hemoglobin

Correct answer: Primarily albumin (the indicator is more sensitive to albumin than other proteins)

The urine dipstick protein pad uses a pH indicator (tetrabromophenol blue) that is primarily sensitive to albumin due to the protein error of indicators principle. It may miss low-molecular-weight proteins like Bence Jones protein (immunoglobulin light chains). Sulfosalicylic acid (SSA) or total protein measurement detects all proteins.

Question 20: What is the significance of the Duffy blood group system in relation to malaria?

Duffy antigens cause malaria
Duffy antigens have no relation to malaria
The Duffy antigen Fy(a)/Fy(b) serves as the receptor for Plasmodium vivax; Duffy-negative individuals are resistant to P. vivax malaria (Correct answer)
Duffy antigens protect against P. falciparum

Correct answer: The Duffy antigen Fy(a)/Fy(b) serves as the receptor for Plasmodium vivax; Duffy-negative individuals are resistant to P. vivax malaria

The Duffy glycoprotein (DARC) serves as the receptor for P. vivax merozoite invasion of red blood cells. The Fy(a-b-) phenotype (common in individuals of West African descent due to a GATA-1 binding site mutation) confers resistance to P. vivax malaria. This selective advantage has maintained the high frequency of the Duffy-null phenotype in malaria-endemic regions.

Question 21: You receive a 24-hour urine collection with a total volume of 1,440 mL. The urine creatinine is 9,504 μmol/L and serum creatinine is 88 μmol/L. Calculate the creatinine clearance in mL/min (use: CrCl = U × V / P, where V is in mL/min).

144 mL/min
95 mL/min
98 mL/min
109 mL/min (Correct answer)

Correct answer: 109 mL/min

V = 1,440 mL ÷ 1,440 min = 1.0 mL/min. CrCl = (9,504 × 1.0) / 88 = 108 ≈ 109 mL/min.

Question 22: In which situation would a laboratory be justified in rejecting a specimen and requesting recollection?

The patient's name on the label has a different spelling than in the LIS due to a known surname change
The specimen is a sodium citrate tube for PT testing that is only 60% full (Correct answer)
The requisition is missing the patient's postal code
The specimen was collected 45 minutes before being received in the laboratory

Correct answer: The specimen is a sodium citrate tube for PT testing that is only 60% full

An underfilled sodium citrate tube (only 60% full instead of the required 90-100% fill) has an improper blood-to-anticoagulant ratio that will falsely prolong PT and APTT, making it unacceptable for coagulation testing.

Question 23: What is the required sample labeling for pre-transfusion testing in Canada?

Patient name only
Two independent patient identifiers on both the sample tube and the requisition, verified at the bedside at the time of collection (Correct answer)
Patient name and room number
Any label is acceptable

Correct answer: Two independent patient identifiers on both the sample tube and the requisition, verified at the bedside at the time of collection

Canadian Standards Association (CSA) standards require positive patient identification at the bedside with two independent identifiers (typically name and unique identifier such as health card number or hospital ID). The sample must be labeled at the bedside, not pre-labeled. Unlabeled or mislabeled samples must be rejected — this is the single most important step in preventing fatal ABO-incompatible transfusions.

Question 24: A patient calls the laboratory directly and demands to know their test results. According to the Regulated Health Professions Act (RHPA) and the scope of practice for medical laboratory professionals in Ontario, what is the correct response?

Provide the results immediately to ensure patient satisfaction.
Tell the patient the results are not ready, even if they are.
Inform the patient that releasing results directly is a form of diagnosis and direct them to their ordering physician. (Correct answer)
Ask the patient to come to the lab in person with photo ID to receive a printed copy.

Correct answer: Inform the patient that releasing results directly is a form of diagnosis and direct them to their ordering physician.

In Ontario, communicating a diagnosis is a controlled act restricted to specific regulated health professionals, such as physicians. Releasing laboratory results directly to a patient is considered a form of communicating a diagnosis and is outside the scope of practice for both MLA/Ts and MLTs. The proper and ethical procedure is to direct the patient back to the ordering healthcare provider who is authorized to interpret and communicate the results in a clinical context.

Question 25: When urine microscopy is performed, the specimen must be centrifuged at 1,500 3,000 rpm for how many minutes?

0
1
5 (Correct answer)
3
15

Correct answer: 5

For urine microscopy, the specimen must be centrifuged at 1,500-3,000 rpm for 5 minutes. This specific centrifugation speed and duration are optimized to concentrate the formed elements (cells, casts, crystals) in the urine sediment. It ensures these delicate structures are concentrated enough for microscopic examination without causing excessive damage or distortion, allowing for accurate identification.

Question 26: Rheumatoid factor (RF) is typically an autoantibody of which immunoglobulin class directed against:

IgG directed against nuclear antigens
IgM directed against patient's own IgG (Correct answer)
IgE directed against IgM
IgA directed against collagen

Correct answer: IgM directed against patient's own IgG

Rheumatoid factor is classically an IgM autoantibody that targets the Fc region of the patient's own IgG, forming immune complexes that contribute to inflammation in rheumatoid arthritis.

Question 27: What is the primary buffer system in human blood plasma?

Bicarbonate-carbonic acid buffer system (Correct answer)
Phosphate buffer system
Protein buffer system
Hemoglobin buffer system

Correct answer: Bicarbonate-carbonic acid buffer system

The bicarbonate-carbonic acid buffer system is the primary buffer in blood plasma, maintaining pH between 7.35 and 7.45. This system is regulated by both the lungs (CO2 excretion) and kidneys (bicarbonate reabsorption), making it highly effective at maintaining acid-base balance.

Question 28: What is the difference between leukoreduction and irradiation of blood products?

Leukoreduction removes white blood cells to prevent febrile reactions, CMV transmission, and HLA alloimmunization; irradiation inactivates residual lymphocytes to prevent TA-GVHD (Correct answer)
Leukoreduction prevents TA-GVHD; irradiation prevents febrile reactions
Both are required for all transfusions
They serve the same purpose

Correct answer: Leukoreduction removes white blood cells to prevent febrile reactions, CMV transmission, and HLA alloimmunization; irradiation inactivates residual lymphocytes to prevent TA-GVHD

Leukoreduction (filtration to <5 × 10⁶ residual WBCs) prevents febrile non-hemolytic transfusion reactions, CMV transmission, and HLA alloimmunization. In Canada, all red cells and platelets are pre-storage leukoreduced. Irradiation (25 Gy gamma) inactivates residual T lymphocytes to prevent TA-GVHD in susceptible patients. They serve different, complementary purposes.

Question 29: What does a 'left shift' in the white blood cell differential indicate?

An increase in mature lymphocytes
A decrease in all white blood cell types
An increase in immature granulocytes (bands and metamyelocytes) indicating active infection (Correct answer)
An increase in eosinophils

Correct answer: An increase in immature granulocytes (bands and metamyelocytes) indicating active infection

A left shift refers to an increase in immature granulocytes (particularly band neutrophils, but also metamyelocytes and myelocytes) in peripheral blood. This indicates the bone marrow is releasing cells prematurely in response to increased demand, typically from bacterial infection or inflammation.

Question 30: A patient has PT 18 seconds (normal 11-14), aPTT 45 seconds (normal 25-35), low fibrinogen, elevated D-dimer, and schistocytes on smear. What is the most likely diagnosis?

Disseminated intravascular coagulation (Correct answer)
Vitamin K deficiency
Primary fibrinolysis
Liver cirrhosis

Correct answer: Disseminated intravascular coagulation

The combination of prolonged PT and aPTT, low fibrinogen, elevated D-dimer, and schistocytes is the classic laboratory picture of DIC. This consumptive coagulopathy results in simultaneous coagulation factor consumption, fibrinolysis activation, and microangiopathic hemolysis. The underlying cause must be identified and treated.

Question 31: What organism should be suspected when a laboratory worker observes small, gram-negative coccobacilli growing on chocolate agar but not on blood agar?

Haemophilus influenzae (Correct answer)
Streptococcus pneumoniae
Escherichia coli
Pseudomonas aeruginosa

Correct answer: Haemophilus influenzae

Haemophilus influenzae requires both X factor (hemin) and V factor (NAD) for growth. Chocolate agar provides both factors through heated blood, while blood agar provides only X factor (V factor is not released from intact RBCs). This differential growth pattern is a key presumptive identification method.

Question 32: What is the difference between forward (cell) typing and reverse (serum) typing in ABO grouping?

Forward typing is performed first; reverse typing is a confirmation only
They test for the same thing using different reagents
Forward typing detects antigens on patient red cells using known anti-A and anti-B; reverse typing detects antibodies in patient serum using known A and B cells (Correct answer)
Forward typing uses patient serum; reverse typing uses patient cells

Correct answer: Forward typing detects antigens on patient red cells using known anti-A and anti-B; reverse typing detects antibodies in patient serum using known A and B cells

Forward typing identifies ABO antigens on patient red blood cells by testing with known anti-A and anti-B reagents. Reverse typing detects ABO antibodies in patient serum/plasma by testing against known A1 and B reagent red cells. Both must agree for a valid ABO type. Discrepancies require investigation before issuing blood.

Question 33: A patient has hemoglobin 95 g/L, MCV 72 fL, HbA2 5.8%, and normal iron studies. What is the most likely diagnosis?

Beta-thalassemia trait (Correct answer)
Alpha-thalassemia trait
Iron deficiency anemia
Anemia of chronic disease

Correct answer: Beta-thalassemia trait

Microcytic anemia with elevated HbA2 (>3.5%) and normal iron studies is the classic pattern for beta-thalassemia trait. The reduced beta-globin chain production leads to a relative excess of delta-chains, increasing HbA2. Iron studies are normal because the anemia is not due to iron deficiency.

Question 34: Which of the following items is NOT found in cryoprecipitate?

Factor XII
Factor V (Correct answer)
Factor VIII
Factor 1
Fibrinogen

Correct answer: Factor V

Cryoprecipitate is a concentrated plasma derivative rich in specific clotting factors that precipitate out when fresh frozen plasma is thawed at cold temperatures. It primarily contains Factor I (fibrinogen), Factor VIII, Factor XIII, and von Willebrand factor. Factor V, however, remains in the cryoprecipitate-poor plasma and is therefore not found in significant amounts in cryoprecipitate.

Question 35: What does 'aliquoting' a specimen mean in laboratory specimen processing?

Filtering a specimen to remove particulates
Mixing a specimen by inversion before analysis
Discarding excess specimen after analysis
Dividing a primary specimen into smaller portions for multiple tests or storage (Correct answer)

Correct answer: Dividing a primary specimen into smaller portions for multiple tests or storage

Aliquoting involves transferring measured portions of a primary specimen into secondary tubes or containers to allow multiple tests to be performed from a single collection or for archival storage.

Question 36: A D-negative pregnant woman at 28 weeks gestation has a negative antibody screen. What action should be taken?

Perform a Kleihauer-Betke test immediately
Induce labour early
Administer antenatal Rh immune globulin (RhIg) at 28 weeks as prophylaxis (Correct answer)
No action needed

Correct answer: Administer antenatal Rh immune globulin (RhIg) at 28 weeks as prophylaxis

Standard of care in Canada is to administer antenatal RhIg (300 µg IM) at 28 weeks gestation to D-negative women with negative antibody screens. This prevents sensitization from small fetomaternal hemorrhages that may occur during the third trimester. Additional RhIg is given postpartum within 72 hours if the baby is D-positive.

Question 37: A patient requests access to their own laboratory test results. Under the Personal Health Information Protection Act (PHIPA) in Ontario, what is the laboratory's obligation?

Direct the patient to the hospital records department exclusively
Provide access only if the physician provides written consent
Refuse, as results must go through the ordering physician only
Provide access within 30 days with limited exceptions (Correct answer)

Correct answer: Provide access within 30 days with limited exceptions

PHIPA grants patients the right to access their own personal health information within 30 days of a request, with limited exceptions such as risk of serious harm.

Question 38: What is the purpose of the daily performance verification (DPV) for point-of-care testing (POCT) devices?

To verify the POCT device performs within acceptable limits using quality control materials before patient testing (Correct answer)
To recalibrate the POCT device using primary standards
To verify the test strips have not expired
To download updated software to the POCT device

Correct answer: To verify the POCT device performs within acceptable limits using quality control materials before patient testing

Daily performance verification using QC materials confirms that the POCT device (e.g., glucometer, i-STAT) is functioning correctly before patient results are generated, ensuring result reliability.

Question 39: Under Biosafety Level 2 (BSL-2) laboratory requirements in Canada, which personal protective equipment is mandatory when handling specimens suspected of containing bloodborne pathogens?

Gloves and eye protection only
Gloves, laboratory coat, and eye protection (Correct answer)
Full-body suit, gloves, and respiratory protection
Gloves only

Correct answer: Gloves, laboratory coat, and eye protection

BSL-2 standard precautions require gloves, a laboratory coat or gown, and eye/face protection when handling potentially infectious bloodborne materials.

Question 40: What is the warm autoimmune hemolytic anemia (WAIHA) and how does it complicate transfusion?

A platelet disorder
IgG autoantibodies that react with patient's own red cells at 37°C, causing hemolysis and making crossmatch incompatible with all donor units (Correct answer)
A cold-reactive antibody disorder
An ABO incompatibility disorder

Correct answer: IgG autoantibodies that react with patient's own red cells at 37°C, causing hemolysis and making crossmatch incompatible with all donor units

WAIHA is caused by IgG autoantibodies (usually anti-e or anti-Rh specificity) that react at 37°C with the patient's own red cells. The autoantibody reacts with all panel cells and all donor units appear incompatible. Special techniques (autoabsorption, alloadsorption) are needed to exclude underlying alloantibodies. 'Least incompatible' blood may need to be issued in life-threatening situations.

Question 41: Which condition is characterized by the presence of target cells (codocytes) on a peripheral blood smear?

Megaloblastic anemia
Thalassemia and liver disease (Correct answer)
Immune hemolytic anemia
Iron deficiency anemia only

Correct answer: Thalassemia and liver disease

Target cells are commonly seen in thalassemia (due to excess membrane relative to hemoglobin content), liver disease (due to altered membrane lipid composition), hemoglobin C disease, and post-splenectomy states. Their bull's-eye appearance results from excess membrane folding.

Question 42: Which medium is specifically used for isolating Neisseria gonorrhoeae?

Thayer-Martin agar (modified) (Correct answer)
Sabouraud dextrose agar
MacConkey agar
Hektoen enteric agar

Correct answer: Thayer-Martin agar (modified)

Modified Thayer-Martin agar is a chocolate agar-based selective medium containing antibiotics (vancomycin, colistin, nystatin, and trimethoprim) that suppress normal flora while allowing N. gonorrhoeae to grow. The organism requires CO2 enrichment (5-10%) and grows best at 35-37°C.

Question 43: What is the Friedewald equation used to calculate?

HDL cholesterol
VLDL cholesterol
LDL cholesterol (Correct answer)
Total cholesterol

Correct answer: LDL cholesterol

The Friedewald equation estimates LDL cholesterol: LDL = Total Cholesterol - HDL - (Triglycerides/2.2) in mmol/L. This equation is unreliable when triglycerides exceed 4.5 mmol/L or when chylomicrons are present, requiring direct LDL measurement instead.

Question 44: A peripheral blood smear differential count shows: neutrophils 68%, lymphocytes 22%, monocytes 7%, eosinophils 2%, basophils 1%. The WBC count is 8.0 × 10⁹/L. What is the absolute neutrophil count (ANC)?

54.4 × 10⁹/L
5.44 × 10⁹/L (Correct answer)
6.80 × 10⁹/L
0.68 × 10⁹/L

Correct answer: 5.44 × 10⁹/L

ANC = WBC × (Neutrophil% ÷ 100) = 8.0 × (68 ÷ 100) = 8.0 × 0.68 = 5.44 × 10⁹/L.

Question 45: What is the correct storage temperature for platelets and what is their shelf life?

Room temperature without agitation for 3 days
20-24°C with continuous gentle agitation for 5-7 days (Correct answer)
Frozen at -18°C for 12 months
1-6°C for 42 days

Correct answer: 20-24°C with continuous gentle agitation for 5-7 days

Platelets are stored at 20-24°C with continuous gentle agitation to maintain gas exchange and prevent clumping. The shelf life is 5 days (or 7 days with pathogen reduction technology). The short shelf life and room temperature storage make platelets susceptible to bacterial contamination, which is monitored by bacterial detection systems.

Question 46: What is the principle of the leukocyte esterase test on the dipstick?

It detects an enzyme released from lysed granulocytes (neutrophils), indicating pyuria (Correct answer)
It detects intact white blood cells by size
It measures white blood cell count directly
It detects bacteria in the urine

Correct answer: It detects an enzyme released from lysed granulocytes (neutrophils), indicating pyuria

The leukocyte esterase test detects esterase enzyme released from lysed neutrophils. It indicates pyuria (white blood cells in urine) and suggests inflammation or infection. It can be positive even when intact WBCs are not seen microscopically because it detects enzyme from lysed cells. Combined with nitrite, it has good negative predictive value for UTI.

Question 47: According to the Clinical and Laboratory Standards Institute (CLSI) which type of water should be used for routine laboratory assays?

Clinical Laboratory Reagent Water (CLRW) (Correct answer)
De-ionized water
Distilled water
Double distilled water (DDH,O)
Filtered water

Correct answer: Clinical Laboratory Reagent Water (CLRW)

According to the Clinical and Laboratory Standards Institute (CLSI), Clinical Laboratory Reagent Water (CLRW) is the standard for routine laboratory assays. CLRW, formerly known as Type I water, has stringent specifications for microbial count, resistivity, and organic contaminants. This ensures it is free from impurities that could interfere with test results, maintaining the accuracy and reliability of diagnostic tests.

Question 48: Where there is a risk of aerosol production, Level 2 containment requires a minimum of:

Level 2 biosafety cabinet
Laminar flow hood
Level 3 biosafety cabinet
Level 1 biosafety cabinet (Correct answer)
No special hood required

Correct answer: Level 1 biosafety cabinet

For Level 2 containment, when there is a risk of aerosol production, a Class I or Class II biosafety cabinet (BSC) is required. These cabinets, often referred to as Level 1 biosafety cabinets in some contexts, provide essential personnel and environmental protection. They achieve this by filtering exhaust air and maintaining an inward airflow, effectively containing aerosols and preventing their release into the laboratory environment.

Question 49: Which coagulation test measures the extrinsic and common pathways?

Activated partial thromboplastin time (aPTT)
Prothrombin time (PT) (Correct answer)
Fibrinogen assay
Thrombin time (TT)

Correct answer: Prothrombin time (PT)

The prothrombin time (PT) measures the extrinsic (Factor VII) and common (Factors X, V, II, and fibrinogen) coagulation pathways. It is triggered by adding tissue thromboplastin (tissue factor) and calcium to citrated plasma. PT/INR is used to monitor warfarin therapy.

Question 50: Which type of error is characterized by results that are consistently higher or lower than the true value?

Preanalytical error
Gross error
Random error
Systematic error (bias) (Correct answer)

Correct answer: Systematic error (bias)

Systematic error (bias) produces results that are consistently displaced in one direction from the true value. It can be constant (same magnitude regardless of concentration) or proportional (error changes with concentration). Causes include calibration errors, reagent deterioration, and matrix effects.

Question 51: A medical laboratory technologist is working alone in the laboratory late at night. Which safety practice is most critical in this situation?

Informing a supervisor or following the laboratory's lone-worker safety protocol (Correct answer)
Avoiding specimen processing until colleagues arrive
Working twice as fast to finish before others arrive
Disabling the laboratory door alarms for easier access

Correct answer: Informing a supervisor or following the laboratory's lone-worker safety protocol

Lone worker policies require that employees working alone inform their supervisor, check in at defined intervals, and ensure someone can respond in case of emergency.

Question 52: What is the catalase test used for in microbiology?

Detecting spore-forming bacteria
Differentiating aerobic from anaerobic bacteria
Identifying gram-negative rods
Differentiating Staphylococcus (positive) from Streptococcus (negative) (Correct answer)

Correct answer: Differentiating Staphylococcus (positive) from Streptococcus (negative)

The catalase test differentiates staphylococci (catalase-positive, produce bubbles when exposed to hydrogen peroxide) from streptococci and enterococci (catalase-negative). Catalase breaks down hydrogen peroxide into water and oxygen gas, producing visible bubbles.

Question 53: In patients receiving intravenous (IV) infusions, what is the correct approach when drawing blood specimens from the same arm?

Draw specimens from above the IV site while the infusion is running
Draw directly from the IV catheter for convenience
Use the arm with IV access as first preference to minimize patient discomfort
Stop the infusion, wait at least 2 minutes, collect distal to the IV site, and note the location on the requisition (Correct answer)

Correct answer: Stop the infusion, wait at least 2 minutes, collect distal to the IV site, and note the location on the requisition

Blood should not be collected from the same arm as an IV infusion. If unavoidable, stop the infusion for at least 2 minutes, collect below (distal to) the IV site, and note the IV fluid and collection site on the requisition.

Question 54: What does the D-dimer test measure and what is its primary clinical application?

Fibrin degradation products from cross-linked fibrin; ruling out venous thromboembolism (Correct answer)
Fibrin monomer levels; diagnosing DIC
Factor V activity; monitoring warfarin
Platelet activation markers; diagnosing HIT

Correct answer: Fibrin degradation products from cross-linked fibrin; ruling out venous thromboembolism

D-dimer measures degradation products from cross-linked fibrin, indicating that both thrombin generation (clot formation) and plasmin activity (clot breakdown) have occurred. Its primary clinical use is ruling out deep vein thrombosis and pulmonary embolism due to its high negative predictive value.

Question 55: What is the significance of Auer rods found on a peripheral blood smear?

They are pathognomonic for acute myeloid leukemia (Correct answer)
They indicate viral infection
They indicate vitamin B12 deficiency
They suggest iron overload

Correct answer: They are pathognomonic for acute myeloid leukemia

Auer rods are needle-shaped, reddish-purple crystalline inclusions found in the cytoplasm of myeloid blast cells. They are pathognomonic (uniquely diagnostic) for acute myeloid leukemia and are never seen in acute lymphoblastic leukemia or benign conditions. Multiple Auer rods (faggot cells) are characteristic of acute promyelocytic leukemia (APL/M3).

Question 56: What is the clinical significance of a positive urine drug screen?

It measures exact drug concentrations
It is always accurate and requires no confirmation
It is a preliminary screening result that requires confirmatory testing (typically mass spectrometry) before clinical or legal decisions; false positives from cross-reacting substances are common (Correct answer)
It definitively proves drug use

Correct answer: It is a preliminary screening result that requires confirmatory testing (typically mass spectrometry) before clinical or legal decisions; false positives from cross-reacting substances are common

Urine drug screens (immunoassay-based) are screening tests with known cross-reactivities. False positives include: poppy seeds (opiates), decongestants (amphetamines), quinolones (amphetamines), and sertraline (benzodiazepines). Positive screening results must be confirmed by a definitive method (GC-MS or LC-MS/MS) before clinical, employment, or legal decisions are made.

Question 57: Which anticoagulant is used in tubes for the complete blood count (CBC)?

EDTA (ethylenediaminetetraacetic acid) (Correct answer)
Lithium heparin
Sodium fluoride
Sodium citrate

Correct answer: EDTA (ethylenediaminetetraacetic acid)

EDTA (lavender-top tube) is the anticoagulant of choice for CBC testing because it preserves cell morphology and prevents platelet clumping. EDTA chelates calcium ions, preventing coagulation while maintaining cellular integrity for accurate automated and manual cell counting.

Question 58: A patient with a mechanical heart valve has an INR target of 2.5-3.5. Their current INR is 2.0. What action should be taken?

No change needed, this is within range
Add aspirin instead of adjusting warfarin
Discontinue warfarin
Increase the warfarin dose slightly to achieve the higher target range (Correct answer)

Correct answer: Increase the warfarin dose slightly to achieve the higher target range

Patients with mechanical heart valves require higher INR targets (typically 2.5-3.5 depending on valve position and type) compared to patients with atrial fibrillation or venous thromboembolism (target 2.0-3.0). An INR of 2.0 is below the therapeutic range and requires a modest dose increase.

Question 59: What is the function of the gel separator in an evacuated blood collection tube?

Plasma from serum
Buffy coat from plasma
RBCS and WBCS from plasma and serum (Correct answer)
RBCS from WBCS
RBCS and WBCS from buffy coat

Correct answer: RBCS and WBCS from plasma and serum

The gel separator in an evacuated blood collection tube forms a stable physical barrier between the cellular components (red blood cells and white blood cells) and the liquid portion (plasma or serum) after centrifugation. This separation prevents metabolic activity of the cells from altering analyte concentrations in the plasma or serum. It ensures sample integrity and allows for accurate testing of various analytes.

Question 60: A physician orders 'type-specific blood' for a patient in moderate hemorrhage. What does the blood bank provide?

Fully crossmatched blood only
Group O blood without testing
Autologous blood
ABO/Rh-type-specific blood with an abbreviated crossmatch (immediate spin) before full testing is complete (Correct answer)

Correct answer: ABO/Rh-type-specific blood with an abbreviated crossmatch (immediate spin) before full testing is complete

Type-specific blood means ABO and Rh-compatible blood based on the patient's confirmed blood type, issued with an abbreviated (immediate-spin) crossmatch or before the antibody screen is complete. This provides blood faster than a full crossmatch while still ensuring ABO compatibility. The full type and screen/crossmatch is completed as soon as possible.

Question 61: For which of the following specimens is maintaining sterility during collection of utmost importance to ensure accurate results?

Blood specimen for a lipid panel
24-hour urine for creatinine clearance
Random urine for routine urinalysis
Urine for culture and sensitivity (Correct answer)

Correct answer: Urine for culture and sensitivity

When collecting a urine specimen for culture and sensitivity, the goal is to identify and quantify bacteria from a potential urinary tract infection. Contamination of the specimen with bacteria from the skin or surrounding environment can lead to false-positive results and inappropriate antibiotic treatment. Therefore, a sterile container and a 'mid-stream clean catch' technique are essential.

Question 62: How should a CSF specimen be prioritized if the volume is limited?

All tests have equal priority
Cell count and differential first (tube 1), then chemistry/serology (tube 2), then microbiology (tube 3 — least likely contaminated) (Correct answer)
Chemistry first, then culture, then cell count
Culture first, then cell count, then chemistry

Correct answer: Cell count and differential first (tube 1), then chemistry/serology (tube 2), then microbiology (tube 3 — least likely contaminated)

When CSF volume is limited, prioritization depends on clinical suspicion. Generally: Tube 1 (cell count — most affected by traumatic tap, so use first tube), Tube 2 (chemistry/protein/glucose), Tube 3 (Gram stain and culture — last tube is least contaminated by blood from traumatic tap). However, if meningitis is strongly suspected, microbiology may take priority.

Question 63: The administration of CPR on an adult requires how many chest compressions performed immediately before a series of two breaths is given?

30 (Correct answer)
25
0
5
20

Correct answer: 30

According to current CPR guidelines for adults, the recommended ratio of chest compressions to breaths is 30 compressions followed by 2 breaths. This sequence should be repeated until emergency medical services arrive or the person shows signs of recovery. Maintaining a compression rate of 100-120 compressions per minute is also crucial for effective CPR.

Question 64: A sample has a platelet count of 50 × 10⁹/L by impedance but the smear shows platelet clumps. What should the technologist do?

Request a new EDTA sample only
Recollect in a sodium citrate tube to rule out EDTA-dependent pseudothrombocytopenia (Correct answer)
Report the result as is
Report as critically low and notify physician immediately

Correct answer: Recollect in a sodium citrate tube to rule out EDTA-dependent pseudothrombocytopenia

Platelet clumping in EDTA is a well-known cause of pseudothrombocytopenia. EDTA can cause antibody-mediated platelet clumping in some patients. Recollection in sodium citrate (blue-top) often resolves the clumping. The platelet count from the citrate tube must be multiplied by 1.1 to correct for the dilution factor.

Question 65: What does the acronym RACE stand for in the context of fire safety response in a healthcare laboratory?

Rescue, Alarm, Contain, Extinguish (Correct answer)
Report, Assess, Call, Evacuate
Rescue, Alert, Contain, Escape
Remove, Alert, Contain, Extinguish

Correct answer: Rescue, Alarm, Contain, Extinguish

RACE stands for Rescue (move patients/personnel from immediate danger), Alarm (activate fire alarm), Contain (close doors to limit fire spread), Extinguish (use a fire extinguisher if safe).

Question 66: A CSF specimen has elevated protein, low glucose, elevated WBC with neutrophil predominance, and the Gram stain shows gram-negative diplococci. What is the most likely pathogen?

Haemophilus influenzae
Listeria monocytogenes
Streptococcus pneumoniae
Neisseria meningitidis (Correct answer)

Correct answer: Neisseria meningitidis

Gram-negative diplococci (kidney-bean shaped) in CSF with a bacterial meningitis profile (high protein, low glucose, neutrophilic pleocytosis) is classic for Neisseria meningitidis. This is a medical emergency requiring immediate ceftriaxone therapy and close contact prophylaxis with rifampin or ciprofloxacin. It is reportable to public health.

Question 67: What is transfusion-related acute lung injury (TRALI)?

A chronic lung condition from repeated transfusions
Fluid overload from too much blood
An allergic reaction causing asthma
Acute respiratory distress occurring within 6 hours of transfusion, caused by donor antibodies activating recipient neutrophils in pulmonary capillaries (Correct answer)

Correct answer: Acute respiratory distress occurring within 6 hours of transfusion, caused by donor antibodies activating recipient neutrophils in pulmonary capillaries

TRALI is a serious complication characterized by acute bilateral pulmonary edema and hypoxia within 6 hours of transfusion, without other risk factors for acute lung injury. It is caused by donor anti-HLA or anti-HNA antibodies that activate recipient neutrophils in pulmonary capillaries. Risk reduction strategies include using male-only plasma donors.

Question 68: Which infection control precaution is implemented when Clostridioides difficile infection is suspected?

Airborne precautions with N95 respirator
Droplet precautions only
Contact precautions with hand washing using soap and water (not alcohol-based hand rub) (Correct answer)
Standard precautions only

Correct answer: Contact precautions with hand washing using soap and water (not alcohol-based hand rub)

C. difficile requires contact precautions including gown and gloves, with hand hygiene using soap and water. Alcohol-based hand sanitizers do NOT kill C. difficile spores. Enhanced environmental cleaning with sporicidal agents (dilute bleach) is also essential as spores can persist on surfaces for months.

Question 69: A urine culture grows more than 100,000 CFU/mL of a single organism. What does this indicate?

Normal flora
Significant bacteriuria consistent with urinary tract infection (Correct answer)
Contamination
Specimen collection error

Correct answer: Significant bacteriuria consistent with urinary tract infection

Growth of ≥10⁵ CFU/mL (100,000 CFU/mL) of a single organism from a clean-catch midstream urine is considered significant bacteriuria. This threshold, combined with clinical symptoms, supports the diagnosis of UTI. Lower counts may be significant in catheterized specimens or symptomatic patients.

Question 70: A blood sample for lactate analysis is drawn in a grey-top (sodium fluoride/potassium oxalate) tube. The test cannot be performed immediately. What is the proper short-term storage condition for this specimen to ensure stability?

Placed in a 37°C heat block
Left at room temperature on the bench
Refrigerated on an ice/water slurry (Correct answer)
Frozen at -20°C

Correct answer: Refrigerated on an ice/water slurry

Sodium fluoride is an antiglycolytic agent that inhibits the enzymatic breakdown of glucose (glycolysis), which produces lactate. However, this process is only slowed, not stopped completely. Chilling the specimen on an ice/water slurry significantly slows down any residual cellular metabolism, preserving the in-vivo lactate concentration until the sample can be centrifuged and analyzed.

Question 71: What investigation must be performed when a transfusion reaction is suspected?

Continue transfusion at a slower rate
Stop transfusion, clerical check, visual inspection of post-transfusion sample for hemolysis, DAT, repeat ABO/Rh on pre- and post-transfusion samples (Correct answer)
No investigation needed if symptoms resolve
Only check the patient's temperature

Correct answer: Stop transfusion, clerical check, visual inspection of post-transfusion sample for hemolysis, DAT, repeat ABO/Rh on pre- and post-transfusion samples

Transfusion reaction investigation includes: 1) Stop the transfusion immediately, 2) Clerical verification of patient and unit identification, 3) Visual inspection for hemolysis (pink/red serum), 4) DAT on post-transfusion sample, 5) Repeat ABO/Rh typing on pre- and post-transfusion samples, 6) Notify blood bank. Additional tests may include urinalysis, bilirubin, haptoglobin, and LDH.

Question 72: A medical laboratory technologist discovers that a refrigerator used to store patient specimens has been at 15°C for an unknown period. What is the correct immediate action?

Discard all specimens without documentation
Continue using specimens if they appear normal visually
Quarantine all affected specimens and notify the supervisor (Correct answer)
Retest all affected specimens immediately without reporting the incident

Correct answer: Quarantine all affected specimens and notify the supervisor

Temperature excursions require immediate quarantine of affected specimens and supervisor notification to assess specimen viability and determine appropriate corrective action.

Question 73: What is the indole test used for, and which organism is characteristically indole-positive?

Detecting tryptophan degradation; Escherichia coli (Correct answer)
Detecting H2S production; Salmonella
Detecting urease activity; Proteus
Detecting citrate utilization; Klebsiella

Correct answer: Detecting tryptophan degradation; Escherichia coli

The indole test detects the ability of bacteria to produce indole from tryptophan via the enzyme tryptophanase. Escherichia coli is characteristically indole-positive, which helps differentiate it from other Enterobacterales. Indole is detected by adding Kovac's or Ehrlich's reagent, producing a red colour.

Question 74: What does a positive urine glucose test indicate?

The patient is always diabetic
Normal carbohydrate metabolism
Glucosuria, which occurs when blood glucose exceeds the renal threshold (approximately 10 mmol/L) or the tubular reabsorption capacity is impaired (Correct answer)
Urinary tract infection

Correct answer: Glucosuria, which occurs when blood glucose exceeds the renal threshold (approximately 10 mmol/L) or the tubular reabsorption capacity is impaired

Glucose in urine (glucosuria) occurs when blood glucose exceeds the renal threshold for glucose reabsorption (approximately 10 mmol/L or 180 mg/dL). Common causes include diabetes mellitus (most common), gestational diabetes, and renal glucosuria (low renal threshold). SGLT2 inhibitor medications also cause glucosuria therapeutically.

Question 75: Which of the following best describes the purpose of the Medical Laboratory Technology Act in Ontario?

To set laboratory fee schedules under OHIP
To define the educational requirements for entry to MLT programs in Ontario colleges
To authorize the self-regulation of the medical laboratory technology profession and define its scope and controlled acts (Correct answer)
To establish laboratory accreditation standards for Ontario hospitals

Correct answer: To authorize the self-regulation of the medical laboratory technology profession and define its scope and controlled acts

The Medical Laboratory Technology Act (1991) is profession-specific legislation that establishes the CMLTO, defines the scope of practice, authorized controlled acts, and the framework for self-regulation of the MLT profession in Ontario.

Question 76: What does an elevated serum creatinine level primarily indicate?

Muscle inflammation
Liver dysfunction
Dehydration only
Decreased glomerular filtration rate (Correct answer)

Correct answer: Decreased glomerular filtration rate

Elevated serum creatinine primarily indicates decreased glomerular filtration rate (GFR) and impaired kidney function. Creatinine is a byproduct of muscle metabolism that is freely filtered by the glomerulus and not significantly reabsorbed, making it a useful marker for renal function.

Question 77: What does a high serum ferritin level with low serum iron and low TIBC suggest?

Hemochromatosis
Iron deficiency anemia
Anemia of chronic disease (Correct answer)
Sideroblastic anemia

Correct answer: Anemia of chronic disease

Anemia of chronic disease (ACD) is characterized by high ferritin (reflecting adequate iron stores), low serum iron (iron is sequestered and unavailable), and low TIBC (reduced transferrin production). This pattern distinguishes ACD from iron deficiency, where ferritin is low and TIBC is elevated.

Question 78: Which of the following is the most appropriate site for capillary blood collection in a premature neonate?

Earlobe
Medial or lateral plantar surface of the heel (Correct answer)
Big toe
Fingertip of the third or fourth finger

Correct answer: Medial or lateral plantar surface of the heel

The medial or lateral plantar surface of the heel is the approved capillary collection site for neonates and premature infants. Fingertips must never be used in neonates due to risk of bone injury.

Question 79: What is the maximum acceptable cold ischemia time for a kidney transplant organ from declaration of brain death to organ reperfusion?

48-72 hours
12-36 hours (Correct answer)
2-4 hours
6-12 hours

Correct answer: 12-36 hours

Cold ischemia time for kidneys is generally acceptable up to 24-36 hours with proper cold perfusion preservation, though outcomes improve significantly with shorter times (<12 hours).

Question 80: What is the normal adult reference range for hemoglobin in males?

110-140 g/L
130-170 g/L (Correct answer)
100-120 g/L
150-200 g/L

Correct answer: 130-170 g/L

The normal hemoglobin range for adult males is approximately 130-170 g/L (or 13.0-17.0 g/dL). This is higher than the female reference range (120-160 g/L) due to the stimulatory effect of testosterone on erythropoiesis and the absence of menstrual blood loss.

Question 81: What is the mechanism of action of warfarin?

Enhancement of antithrombin activity
Direct thrombin inhibition
Irreversible platelet COX-1 inhibition
Inhibition of vitamin K epoxide reductase, reducing functional vitamin K-dependent factor synthesis (Correct answer)

Correct answer: Inhibition of vitamin K epoxide reductase, reducing functional vitamin K-dependent factor synthesis

Warfarin inhibits vitamin K epoxide reductase (VKORC1), blocking the recycling of vitamin K to its active reduced form. This impairs the gamma-carboxylation of vitamin K-dependent coagulation factors (II, VII, IX, X) and proteins C and S, reducing their functional activity.

Question 82: Which white blood cell type is most numerous in normal adult peripheral blood?

Eosinophils
Neutrophils (Correct answer)
Lymphocytes
Monocytes

Correct answer: Neutrophils

Neutrophils are the most abundant white blood cell type in normal adult blood, comprising 40-70% of the total WBC count. They are the primary phagocytic cells of the innate immune system and are the first responders to bacterial infections.

Question 83: A cord blood sample has a positive DAT with anti-IgG. The mother is group O Rh-positive and the baby is group A Rh-positive. What is the most likely cause?

ABO hemolytic disease of the newborn due to maternal anti-A (IgG) crossing the placenta (Correct answer)
Rh HDFN
Autoimmune hemolytic anemia in the newborn
Laboratory error

Correct answer: ABO hemolytic disease of the newborn due to maternal anti-A (IgG) crossing the placenta

The most likely cause is ABO HDFN. Group O mothers produce IgG anti-A and anti-B (in addition to IgM), which can cross the placenta and coat the fetal A or B red cells. ABO HDFN is usually mild but can occasionally cause significant jaundice requiring phototherapy. An eluate from the baby's cells would confirm anti-A.

Question 84: Why is it important to measure ionized calcium rather than total calcium in critically ill patients?

Ionized calcium is less expensive to measure
Ionized calcium represents the biologically active form unaffected by albumin changes (Correct answer)
Ionized calcium is more stable in storage
Total calcium cannot be measured in ICU settings

Correct answer: Ionized calcium represents the biologically active form unaffected by albumin changes

Ionized calcium is the physiologically active form and is preferred in critically ill patients because total calcium is significantly affected by albumin levels, which are frequently abnormal in these patients. Approximately 40% of total calcium is bound to albumin, so hypoalbuminemia can mask true calcium status.

Question 85: A patient is undergoing therapeutic phlebotomy for hereditary hemochromatosis. What is the standard volume of blood removed per session in adult patients?

100-200 mL
450-500 mL (Correct answer)
250-350 mL
700-900 mL

Correct answer: 450-500 mL

The standard therapeutic phlebotomy volume for hereditary hemochromatosis is 450-500 mL per session (equivalent to a whole blood donation), performed weekly or bi-weekly until iron stores normalize.

Question 86: A pleural fluid analysis shows protein 45 g/L, LDH 500 U/L (serum LDH 200 U/L), glucose 2.0 mmol/L, and many lymphocytes. What diagnosis should be considered?

Uncomplicated pneumonia
Pulmonary embolism
Congestive heart failure
Tuberculous pleuritis or malignancy (Correct answer)

Correct answer: Tuberculous pleuritis or malignancy

This is an exudative effusion (high protein, LDH ratio >0.6) with lymphocyte predominance and low glucose. This pattern is characteristic of either tuberculous pleuritis or malignancy. Adenosine deaminase (ADA) levels >40 U/L support TB diagnosis. Cytology and pleural biopsy may be needed for malignancy diagnosis. AFB culture and NAAT for TB should be performed.

Question 87: A Levey-Jennings chart shows five consecutive QC values all falling above the mean on the same side. Which Westgard rule is violated?

R4s rule
1₃s rule
10x rule (Correct answer)
2s rule

Correct answer: 10x rule

The 10x rule (10ₓ) is violated when 10 consecutive control values fall on the same side of the mean, indicating a systematic shift or bias.

Question 88: Which principle underlies the fluorescent treponemal antibody absorption (FTA-ABS) test for syphilis?

Complement fixation using treponemal antigen
Direct ELISA with recombinant treponemal peptides
Latex agglutination with cardiolipin antigen
Indirect immunofluorescence after absorption of non-specific antibodies (Correct answer)

Correct answer: Indirect immunofluorescence after absorption of non-specific antibodies

The FTA-ABS uses indirect immunofluorescence where patient serum is first absorbed with non-pathogenic treponemes to remove cross-reactive antibodies, then applied to Treponema pallidum on a slide and detected with fluorescent anti-human immunoglobulin.

Question 89: What does the prefix 'hypo-' mean in medical terminology?

Above normal
Between
Below normal or deficient (Correct answer)
Excessive

Correct answer: Below normal or deficient

'Hypo-' means below normal, under, or deficient. Examples in laboratory medicine include hypoglycemia (low blood glucose), hypothyroidism (deficient thyroid function), and hyponatremia (low sodium).

Question 90: A patient requires chronic transfusion for sickle cell disease. What special blood bank considerations apply?

Extended phenotype matching (Rh C, c, E, e, and K at minimum) to reduce alloimmunization risk, plus HbS-negative donor units (Correct answer)
No special considerations
Only autologous transfusion
Standard ABO/Rh matching only

Correct answer: Extended phenotype matching (Rh C, c, E, e, and K at minimum) to reduce alloimmunization risk, plus HbS-negative donor units

Sickle cell disease patients have a high alloimmunization rate (25-50%) due to antigen differences between donor (predominantly Caucasian) and recipient (predominantly African descent) populations. Canadian guidelines recommend extended matching for Rh (C, c, E, e) and Kell at minimum. Donor units should be sickle-negative (HbS-negative). Phenotypically similar donors should be actively recruited.

Question 91: What does a positive oxidase test indicate, and which clinically significant organism is oxidase-positive?

Presence of catalase; Staphylococcus aureus
Presence of coagulase; Staphylococcus aureus
Presence of cytochrome c oxidase; Pseudomonas aeruginosa (Correct answer)
Presence of urease; Proteus mirabilis

Correct answer: Presence of cytochrome c oxidase; Pseudomonas aeruginosa

The oxidase test detects the presence of cytochrome c oxidase, an enzyme in the electron transport chain. Pseudomonas aeruginosa is a clinically important oxidase-positive, gram-negative rod. The test uses a reagent (tetramethyl-p-phenylenediamine) that turns dark purple when oxidized by the enzyme.

Question 92: What infectious disease testing is performed on all donated blood in Canada?

No testing is performed; donors are screened by questionnaire only
HIV, Hepatitis B, Hepatitis C, HTLV-I/II, Syphilis, West Nile Virus, and additional tests as required (Correct answer)
Only bacterial culture
HIV testing only

Correct answer: HIV, Hepatitis B, Hepatitis C, HTLV-I/II, Syphilis, West Nile Virus, and additional tests as required

All Canadian blood donations are tested for: HIV-1/2 (antibody and NAT), Hepatitis B (HBsAg, anti-HBc, NAT), Hepatitis C (antibody and NAT), HTLV-I/II (antibody), Syphilis (antibody), and West Nile Virus (NAT). Additional testing (e.g., Babesia, Zika) may be implemented based on risk assessment. Nucleic acid testing (NAT) has significantly narrowed the window period.

Question 93: A medical laboratory technologist receives a specimen with a label discrepancy. What is the most appropriate first action?

Run the test and hold results pending label correction
Contact the requesting clinician or unit to clarify and relabel (Correct answer)
Process the specimen and note the discrepancy in the report
Discard the specimen immediately

Correct answer: Contact the requesting clinician or unit to clarify and relabel

Specimen label discrepancies must be resolved before processing. Contacting the source for clarification and proper relabeling ensures patient safety and result integrity.

Question 94: What is the Henderson-Hasselbalch equation used to calculate in clinical chemistry?

Blood pH from bicarbonate and pCO2 (Correct answer)
Osmolal gap
Anion gap
Creatinine clearance

Correct answer: Blood pH from bicarbonate and pCO2

The Henderson-Hasselbalch equation calculates blood pH from the ratio of bicarbonate concentration to dissolved CO2 (pCO2). The equation is pH = pK + log([HCO3-]/[0.03 × pCO2]), and it is fundamental to understanding acid-base physiology.

Question 95: What is the difference between type 1, type 2, and type 3 von Willebrand disease?

Type 1 affects Factor VIII only; type 2 affects vWF only; type 3 affects both equally
All three types are clinically identical
Type 1 is autosomal recessive; type 2 is X-linked; type 3 is autosomal dominant
Type 1 is quantitative decrease; type 2 is qualitative defect; type 3 is complete absence (Correct answer)

Correct answer: Type 1 is quantitative decrease; type 2 is qualitative defect; type 3 is complete absence

Type 1 vWD (most common, ~70-80%) involves a partial quantitative decrease in vWF. Type 2 involves qualitative vWF defects (subtypes 2A, 2B, 2M, 2N have different functional abnormalities). Type 3 (rarest, most severe) involves complete or near-complete absence of vWF. Treatment varies by type.

Question 96: Which blood culture system is most commonly used in Canadian clinical laboratories?

Lysis-centrifugation (Isolator)
Pour plate method
Automated continuous-monitoring blood culture systems (BacT/ALERT or BACTEC) (Correct answer)
Manual biphasic bottles

Correct answer: Automated continuous-monitoring blood culture systems (BacT/ALERT or BACTEC)

Automated continuous-monitoring blood culture systems (such as bioMérieux BacT/ALERT and Becton Dickinson BACTEC) are the standard in Canadian laboratories. These systems continuously monitor bottles for CO2 production or pH changes indicating microbial growth, providing rapid detection (average 12-36 hours for common pathogens).

Question 97: What is the role of erythropoietin (EPO) in hematopoiesis?

Stimulates white blood cell production
Stimulates platelet production
Inhibits bone marrow stem cell differentiation
Stimulates red blood cell production in response to hypoxia (Correct answer)

Correct answer: Stimulates red blood cell production in response to hypoxia

Erythropoietin is a glycoprotein hormone produced primarily by the kidneys in response to tissue hypoxia. It stimulates erythroid progenitor cells in the bone marrow to proliferate and differentiate into mature red blood cells. Chronic kidney disease reduces EPO production, causing anemia.

Question 98: For a coagulation test such as PT/INR, which is the correct blood-to-anticoagulant ratio in a sodium citrate (blue top) tube?

3:1
9:1 (Correct answer)
1:9
5:1

Correct answer: 9:1

The correct blood-to-anticoagulant ratio for sodium citrate tubes used in coagulation testing is 9 parts blood to 1 part citrate (9:1).

Question 99: What is the principle behind the Kleihauer-Betke (KB) test performed in transfusion medicine?

Detection of HLA antibodies for platelet compatibility
Detection of irregular red cell antibodies in maternal serum
Determination of ABO blood group in a newborn
Quantification of fetal red blood cells in maternal circulation after fetomaternal hemorrhage (Correct answer)

Correct answer: Quantification of fetal red blood cells in maternal circulation after fetomaternal hemorrhage

The Kleihauer-Betke test detects and quantifies fetal RBCs in maternal blood. Fetal hemoglobin (HbF) is acid-resistant; adult hemoglobin (HbA) elutes with acid treatment, leaving ghost cells. Fetal cells appear pink.

Question 100: A patient's urine shows many waxy casts, broad casts, and RTE cells. What does this suggest?

Dehydration only
Acute urinary tract infection
Normal urinalysis
Severe chronic renal disease with tubular damage and stasis (Correct answer)

Correct answer: Severe chronic renal disease with tubular damage and stasis

Waxy casts indicate prolonged urinary stasis in damaged tubules. Broad casts ('renal failure casts') form in dilated, damaged collecting ducts. Renal tubular epithelial (RTE) cells indicate active tubular injury. Together, these findings suggest severe chronic kidney disease with ongoing tubular damage and a poor prognosis.

Question 101: Which type of laboratory waste must be placed in a sharps container in an Ontario medical laboratory?

Used needles, lancets, and broken glass from patient contact (Correct answer)
Used reagent bottles
Broken glass from non-infectious specimens only
All glass materials used in the laboratory

Correct answer: Used needles, lancets, and broken glass from patient contact

Sharps containers are required for needles, lancets, scalpel blades, and any broken glass that has had patient contact, as these pose needlestick and laceration injury risks.

Question 102: Under the Regulated Health Professions Act (RHPA) in Ontario, which controlled act is authorized for medical laboratory technologists?

Administering a substance by injection
Prescribing laboratory tests
Performing a procedure on tissue below the dermis (Correct answer)
Communicating a diagnosis

Correct answer: Performing a procedure on tissue below the dermis

MLTs are authorized to perform procedures on tissue below the dermis as part of specimen collection activities such as venipuncture and skin puncture.

Question 103: What is the purpose of centrifugation in specimen processing in a medical laboratory?

To concentrate bacteria for culture
To mix reagents with the specimen
To lyse red blood cells for analysis
To separate blood into its cellular and liquid components (Correct answer)

Correct answer: To separate blood into its cellular and liquid components

Centrifugation uses centrifugal force to separate blood into its components: packed red cells at the bottom, a buffy coat of white cells and platelets, and serum or plasma on top.

Question 104: A blood smear shows bite cells and Heinz bodies on a supravital stain. The patient recently started taking a sulfonamide antibiotic. What is the most likely diagnosis?

Iron deficiency anemia
Glucose-6-phosphate dehydrogenase (G6PD) deficiency with oxidative hemolysis (Correct answer)
Hereditary spherocytosis
Autoimmune hemolytic anemia

Correct answer: Glucose-6-phosphate dehydrogenase (G6PD) deficiency with oxidative hemolysis

Bite cells (degmacytes) result from splenic removal of Heinz bodies (denatured hemoglobin precipitates). This pattern triggered by an oxidizing drug (sulfonamide) is classic for G6PD deficiency. The deficient enzyme cannot generate adequate NADPH to maintain reduced glutathione, leaving hemoglobin vulnerable to oxidative damage.

Question 105: Which test differentiates Enterococcus from Group D Streptococcus?

Catalase test
Optochin susceptibility
Coagulase test
Growth in 6.5% NaCl broth (Correct answer)

Correct answer: Growth in 6.5% NaCl broth

Enterococci grow in 6.5% NaCl broth while Group D streptococci (S. bovis group) cannot. Both are bile esculin-positive. This salt tolerance test is important because enterococci have different antibiotic resistance patterns and treatment implications than Group D streptococci.

Question 106: Which laboratory finding differentiates thrombotic thrombocytopenic purpura (TTP) from hemolytic uremic syndrome (HUS)?

TTP has severely decreased ADAMTS13 activity; HUS typically does not (Correct answer)
TTP has schistocytes; HUS does not
TTP affects only children; HUS affects only adults
TTP has elevated fibrinogen; HUS has decreased fibrinogen

Correct answer: TTP has severely decreased ADAMTS13 activity; HUS typically does not

TTP is characterized by severely deficient ADAMTS13 activity (<10%), the metalloprotease that cleaves von Willebrand factor multimers. In typical HUS (caused by Shiga toxin-producing E. coli), ADAMTS13 activity is normal. Both conditions show thrombocytopenia, MAHA with schistocytes, and organ damage.

Question 107: Which condition is characterized by elevated serum bilirubin with a predominantly unconjugated (indirect) fraction?

Hepatocellular carcinoma
Cholestasis
Hemolytic anemia (Correct answer)
Biliary obstruction

Correct answer: Hemolytic anemia

Hemolytic anemia causes elevated unconjugated (indirect) bilirubin because the excessive breakdown of red blood cells overwhelms the liver's capacity to conjugate bilirubin. In contrast, obstructive and hepatocellular conditions typically elevate conjugated (direct) bilirubin.

Question 108: What is the primary function of albumin in human plasma?

Coagulation factor synthesis
Maintenance of oncotic pressure and protein transport (Correct answer)
Oxygen transport
Immune defense

Correct answer: Maintenance of oncotic pressure and protein transport

Albumin is the most abundant plasma protein and serves to maintain colloid oncotic pressure (preventing fluid from leaking out of blood vessels) and to transport various substances including hormones, drugs, and bilirubin.

Question 109: A laboratory identifies a Salmonella species from a stool culture. What is the reporting obligation in Canada?

Only typhoid Salmonella needs reporting
Reporting is optional and at the physician's discretion
Salmonella is a reportable/notifiable disease and must be reported to public health authorities (Correct answer)
No reporting is required

Correct answer: Salmonella is a reportable/notifiable disease and must be reported to public health authorities

Salmonellosis is a reportable/notifiable disease in all Canadian provinces and territories. The laboratory must report the isolation to local public health authorities. Isolates may be sent to a reference laboratory for serotyping and molecular typing for outbreak investigation and surveillance purposes.

Question 110: A laboratory is setting up a highly sensitive trace element analysis. According to CLSI standards, what is the minimum grade of reagent water that should be used for preparing calibrators and standards for this procedure?

Type II
Special Reagent Water (SRW)
Type III
Clinical Laboratory Reagent Water (CLRW) (Correct answer)

Correct answer: Clinical Laboratory Reagent Water (CLRW)

Clinical Laboratory Reagent Water (CLRW) is the minimum standard for most routine clinical analyses. It has defined limits for resistivity, bacteria, and total organic carbon. While some highly specialized tests may require Special Reagent Water (SRW) with even stricter limits for specific contaminants, CLRW is the established baseline for preparing most reagents, calibrators, and controls.

Question 111: A urine microscopy shows hexagonal, colourless crystals in acidic urine from a young patient with recurrent kidney stones. What is the diagnosis?

Calcium oxalate stones
Uric acid stones
Struvite stones
Cystinuria with cystine crystals (Correct answer)

Correct answer: Cystinuria with cystine crystals

Hexagonal, colourless crystals in acidic urine are pathognomonic for cystine. Cystinuria is an inherited autosomal recessive disorder of amino acid transport affecting reabsorption of cystine, ornithine, lysine, and arginine (COLA) in the renal tubules. Cystine is poorly soluble, forming recurrent stones. Confirmatory testing includes the cyanide-nitroprusside test and 24-hour urine cystine.

Question 112: Which vitamin is essential for the post-translational carboxylation of coagulation factors II, VII, IX, and X?

Vitamin K (Correct answer)
Vitamin C
Vitamin A
Vitamin B12

Correct answer: Vitamin K

Vitamin K is required for the post-translational carboxylation of glutamate residues on coagulation factors II, VII, IX, X, and the anticoagulant proteins C and S, enabling calcium binding and activation.

Question 113: What are the key differences between thick and thin blood smear examination for malaria diagnosis?

Both have identical purposes
Thick smears concentrate organisms for detection sensitivity; thin smears preserve morphology for species identification (Correct answer)
Thick smears are stained differently from thin smears
Thick smears are for species identification; thin smears are for detection

Correct answer: Thick smears concentrate organisms for detection sensitivity; thin smears preserve morphology for species identification

Thick smears lyse red blood cells and concentrate parasites, providing 10-20 times greater sensitivity for detecting malaria. Thin smears preserve red cell morphology and parasite structure, enabling species identification and parasitemia quantification. Both should be prepared and examined for optimal malaria diagnosis.

Question 114: A transfusion sample is received in the blood bank with a label that has the patient's name but no second identifier. What should be done?

Process if the name matches the requisition
Reject the specimen and request a new properly labeled specimen collected with bedside identification (Correct answer)
Process the specimen using the name alone
Add the missing identifier from the requisition

Correct answer: Reject the specimen and request a new properly labeled specimen collected with bedside identification

A specimen missing a required identifier (two independent identifiers are mandatory) must be rejected. A new specimen must be collected at the bedside with proper patient identification. No exceptions should be made, as mislabeled specimens are the most common cause of fatal transfusion errors. This policy must be enforced consistently.

Question 115: A laboratory's glucose analyzer has a reportable range of 1.0–30.0 mmol/L. A patient result reads 'HI' (above the linear range). The technologist dilutes the specimen 1:4 with saline and obtains a result of 9.8 mmol/L. What is the corrected patient glucose?

2.45 mmol/L
9.8 mmol/L
39.2 mmol/L (Correct answer)
44.0 mmol/L

Correct answer: 39.2 mmol/L

Corrected result = Diluted result × Dilution factor = 9.8 × 4 = 39.2 mmol/L.

Question 116: What is the significance of finding teardrop cells (dacrocytes) on a peripheral blood smear?

Liver cirrhosis
Sickle cell disease
Myelofibrosis or bone marrow infiltration (Correct answer)
Iron deficiency anemia

Correct answer: Myelofibrosis or bone marrow infiltration

Teardrop cells (dacrocytes) are characteristic of myelofibrosis and conditions causing marrow infiltration (myelophthisis). They form as red blood cells are forced through fibrotic bone marrow tissue. The presence of teardrop cells with nucleated red blood cells and immature granulocytes (leukoerythroblastic picture) strongly suggests marrow pathology.

Question 117: During the total testing process, the majority of laboratory errors occur in which phase?

Pre-analytical phase (Correct answer)
Post-analytical phase
Reporting phase
Analytical phase

Correct answer: Pre-analytical phase

Numerous studies have consistently shown that the pre-analytical phase is the most error-prone stage of the total testing process, accounting for up to 70% of all laboratory mistakes. [20, 25, 22] This phase includes patient identification, specimen collection, handling, and transport—all steps that occur before the sample is actually tested. [25, 27]

Question 118: What are the components of pre-transfusion testing (type and screen)?

Crossmatch only
Complete blood count and coagulation panel
ABO/Rh typing and antibody screen (indirect antiglobulin test) (Correct answer)
ABO/Rh typing only

Correct answer: ABO/Rh typing and antibody screen (indirect antiglobulin test)

Pre-transfusion testing includes: 1) ABO grouping (forward and reverse), 2) Rh(D) typing, and 3) antibody screening (indirect antiglobulin test/IAT) to detect unexpected red cell antibodies. If the antibody screen is positive, antibody identification is performed before crossmatch-compatible blood can be issued.

Question 119: Which hormone, produced by the beta cells of the pancreatic islets of Langerhans, promotes cellular glucose uptake?

Epinephrine
Cortisol
Insulin (Correct answer)
Glucagon

Correct answer: Insulin

Insulin, produced by pancreatic beta cells, promotes glucose uptake by cells (especially muscle and adipose tissue) and decreases blood glucose levels after meals.

Question 120: What are the signs and symptoms of an acute hemolytic transfusion reaction?

Fever, chills, flank/back pain, hemoglobinuria, hypotension, DIC, and renal failure (Correct answer)
Only mild itching
Delayed fever occurring 5-10 days after transfusion
Mild urticaria only

Correct answer: Fever, chills, flank/back pain, hemoglobinuria, hypotension, DIC, and renal failure

Acute hemolytic transfusion reactions (usually ABO-incompatible) present with fever, chills, back/flank pain, chest tightness, hemoglobinuria (dark urine), hypotension, and can progress to DIC, shock, and renal failure. Immediate action includes stopping the transfusion, maintaining IV access, and notifying the blood bank for investigation.

Question 121: What is the significance of xanthochromia in cerebrospinal fluid?

It is a normal CSF colour
It indicates bacterial meningitis
It indicates viral meningitis
A yellow discolouration of CSF supernatant indicating the presence of hemoglobin degradation products (bilirubin, oxyhemoglobin), suggesting subarachnoid hemorrhage at least 2-4 hours old (Correct answer)

Correct answer: A yellow discolouration of CSF supernatant indicating the presence of hemoglobin degradation products (bilirubin, oxyhemoglobin), suggesting subarachnoid hemorrhage at least 2-4 hours old

Xanthochromia (yellow discolouration of CSF supernatant after centrifugation) indicates in vivo hemoglobin degradation, distinguishing subarachnoid hemorrhage (SAH) from traumatic tap. It develops 2-4 hours after SAH as RBCs lyse and hemoglobin is converted to oxyhemoglobin and then bilirubin. Spectrophotometric analysis provides objective xanthochromia assessment.

Question 122: Which of the following analytes requires the specimen to be protected from light during collection and transport?

Potassium
Glucose
Bilirubin (Correct answer)
Creatinine

Correct answer: Bilirubin

Bilirubin is a light-sensitive analyte. Exposure to light, especially UV and fluorescent light, causes it to degrade rapidly, leading to falsely low results. Therefore, specimens for bilirubin testing must be collected in amber-colored tubes or wrapped in foil to protect them from light.

Question 123: A patient with HIV has CD4 count below 200 cells/µL and presents with chronic watery diarrhea. Modified acid-fast stain of stool shows small round pink oocysts (4-6 µm). What is the diagnosis?

Cyclosporiasis
Cryptosporidiosis (Correct answer)
Giardiasis
Isosporiasis

Correct answer: Cryptosporidiosis

Cryptosporidium oocysts are 4-6 µm, round, and stain variably pink with modified acid-fast stain. Cryptosporidiosis causes chronic, potentially life-threatening watery diarrhea in severely immunocompromised patients (CD4 <200). Cyclospora oocysts are larger (8-10 µm) and stain variably. Antiretroviral therapy to restore CD4 count is the most effective treatment.

Question 124: When storing serum specimens for up to 7 days pending batch analysis, what is the appropriate storage temperature?

Refrigerator (2-8°C) (Correct answer)
Freezer (-20°C)
Room temperature (15-25°C)
Ultra-low freezer (-70°C) for all analytes

Correct answer: Refrigerator (2-8°C)

For short-term storage (up to 7 days), most serum chemistry analytes are stable when refrigerated at 2-8°C. This temperature slows enzymatic degradation and bacterial growth without causing freeze-thaw damage.

Question 125: In the event of a large chemical spill in the laboratory, the Safety Data Sheet (SDS) is immediately consulted. Which section of the SDS provides the most critical information on how to clean up the spill safely?

Section 4: First-Aid Measures
Section 6: Accidental Release Measures (Correct answer)
Section 8: Exposure Controls/Personal Protection
Section 7: Handling and Storage

Correct answer: Section 6: Accidental Release Measures

Section 6 of a Safety Data Sheet (SDS), titled "Accidental Release Measures," is specifically dedicated to providing procedures for responding to spills, leaks, or releases. This section includes information on containment, cleanup procedures, and necessary precautions to prevent adverse effects on personnel, property, and the environment.

Question 126: A urine specific gravity is measured at 1.010 using a refractometer at a temperature of 27°C. The refractometer is calibrated at 20°C. Each 3°C above 20°C requires adding 0.001 to the reading. What is the corrected specific gravity?

1.010
1.013
1.009
1.012 (Correct answer)

Correct answer: 1.012

Temperature difference = 27 − 20 = 7°C. Correction = 7°C ÷ 3°C × 0.001 = 0.0023 ≈ 0.002. Corrected SG = 1.010 + 0.002 = 1.012.

Question 127: A urine specimen is cloudy with an alkaline pH, positive nitrite, positive leukocyte esterase, and microscopy shows many WBCs, bacteria, and triple phosphate crystals. What is the diagnosis?

Normal concentrated urine
Glomerulonephritis
Urinary tract infection likely caused by a urease-producing organism (Correct answer)
Nephrotic syndrome

Correct answer: Urinary tract infection likely caused by a urease-producing organism

This is a UTI caused by a urease-producing organism (likely Proteus). The urease converts urea to ammonia, creating alkaline urine that promotes triple phosphate (struvite) crystal formation. Positive nitrite confirms bacterial nitrate reduction, and positive leukocyte esterase with many WBCs confirms pyuria. Culture will likely confirm Proteus mirabilis.

Question 128: Which cell type is responsible for producing antibodies?

Plasma cells (Correct answer)
Macrophages
Cytotoxic T lymphocytes
Natural killer cells

Correct answer: Plasma cells

Plasma cells are terminally differentiated B lymphocytes specifically designed to produce and secrete large quantities of antibodies.

Question 129: What is the CAMP test used to identify?

Staphylococcus aureus
Listeria monocytogenes
Group B Streptococcus (Streptococcus agalactiae) (Correct answer)
Enterococcus faecalis

Correct answer: Group B Streptococcus (Streptococcus agalactiae)

The CAMP test identifies Group B Streptococcus (S. agalactiae) by demonstrating enhanced hemolysis in the shape of an arrowhead where the CAMP factor of GBS intersects with the beta-hemolysin of Staphylococcus aureus on a blood agar plate. GBS is a critical pathogen in neonatal sepsis and meningitis.

Question 130: Which body is responsible for regulating medical laboratory technologists in Ontario?

The Canadian Society for Medical Laboratory Science (CSMLS)
The Institute for Quality Management in Healthcare (IQMH)
The Ontario Medical Association (OMA)
The College of Medical Laboratory Technologists of Ontario (CMLTO) (Correct answer)

Correct answer: The College of Medical Laboratory Technologists of Ontario (CMLTO)

The College of Medical Laboratory Technologists of Ontario (CMLTO) is the regulatory body that registers, regulates, and governs medical laboratory technologists in Ontario under the Regulated Health Professions Act.

Question 131: Which specimen type is preferred for most clinical chemistry analyses?

Plasma from a heparin tube
Whole blood in EDTA
Serum from a red-top tube (Correct answer)
Capillary blood

Correct answer: Serum from a red-top tube

Serum collected in a red-top (no additive) tube or serum separator tube (SST) is preferred for most clinical chemistry analyses. Serum lacks fibrinogen and clotting factors, providing a cleaner matrix that minimizes interference with many analytical methods.

Question 132: A Gram stain of a positive blood culture shows gram-positive cocci in clusters. What organism is most likely and what empiric therapy should be communicated?

Staphylococcus species; vancomycin pending identification and susceptibilities (Correct answer)
Enterococcus; ampicillin
Neisseria meningitidis; ceftriaxone
Streptococcus pneumoniae; penicillin

Correct answer: Staphylococcus species; vancomycin pending identification and susceptibilities

Gram-positive cocci in clusters from blood culture is most consistent with Staphylococcus species. Because MRSA must be considered, empiric vancomycin is recommended until species identification and susceptibility results are available. If methicillin-susceptible S. aureus (MSSA) is confirmed, therapy is narrowed to cloxacillin/cefazolin.

Question 133: A technologist notices that the automated WBC count is 25 × 10⁹/L but the histogram shows a suspicious population. The peripheral smear shows many nucleated red blood cells (NRBCs). What should be reported?

The automated WBC count without correction
A corrected WBC count after subtracting NRBCs from the total count (Correct answer)
Only the NRBC count
The automated count with a comment that NRBCs are present but no correction

Correct answer: A corrected WBC count after subtracting NRBCs from the total count

NRBCs have nuclei and are counted as WBCs by automated analyzers that use lysis-resistant nuclear counting. The WBC count must be corrected using the formula: Corrected WBC = (Automated WBC × 100) / (100 + NRBC per 100 WBC). The presence of NRBCs and the corrected count should both be reported.

Question 134: Which serum marker is used to monitor methotrexate therapy toxicity?

Thyroid function tests
Creatinine and liver enzymes (Correct answer)
Cardiac troponin
Serum cortisol

Correct answer: Creatinine and liver enzymes

Creatinine and liver enzymes (AST, ALT) are monitored during methotrexate therapy because the drug can cause both nephrotoxicity and hepatotoxicity. Methotrexate is primarily excreted by the kidneys, and impaired renal function can lead to drug accumulation and increased toxicity.

Question 135: What is the Westgard rule 1₃s in quality control?

A rejection rule triggered when one QC result exceeds 3 SD (Correct answer)
A warning rule when the range of QC results exceeds 4 SD
A rejection rule when two consecutive QC results exceed 2 SD
A warning rule triggered when one QC result exceeds 2 SD

Correct answer: A rejection rule triggered when one QC result exceeds 3 SD

The 1₃s Westgard rule is a rejection rule: if a single quality control result exceeds the mean ± 3 standard deviations, the analytical run must be rejected.

Question 136: What is the principle of flow cytometry immunophenotyping in hematological malignancies?

Identifying cell surface and intracellular markers using fluorescent-labeled antibodies (Correct answer)
Counting cells based on nuclear morphology
Staining cells with Romanowsky dyes
Measuring cell size by impedance

Correct answer: Identifying cell surface and intracellular markers using fluorescent-labeled antibodies

Flow cytometry identifies cell types by using fluorescent-labeled monoclonal antibodies that bind to specific CD (cluster of differentiation) markers on cell surfaces or within cells. Cells pass through a laser beam in single file, and fluorescence patterns identify lineage (myeloid vs. lymphoid) and maturation stage.

Question 137: A patient is scheduled for a Prothrombin Time (PT/INR), a Complete Blood Count (CBC), and a glucose test. Following the CLSI recommended order of draw, which tube should be collected second?

Lavender top (EDTA)
Gray top (Sodium Fluoride/Potassium Oxalate)
Light Blue top (Sodium Citrate) (Correct answer)
Red top (Clot activator)

Correct answer: Light Blue top (Sodium Citrate)

The correct order of draw is crucial to prevent cross-contamination of additives between tubes. According to CLSI guidelines, the sequence is: 1) Blood cultures, 2) Light Blue top (for coagulation tests like PT/INR), 3) Serum tubes (Red/Gold), 4) Heparin tubes (Green), 5) EDTA tubes (Lavender for CBC), and finally 6) Glycolytic inhibitor tubes (Gray for glucose). Therefore, the Light Blue top tube is collected second in this scenario.

Question 138: In flow cytometry, CD4:CD8 ratio is used clinically to monitor patients with HIV. A significantly decreased ratio (below 1.0) indicates:

Polyclonal B cell activation
Progressive immunodeficiency due to CD4+ T cell depletion (Correct answer)
A normal healthy immune response
Increased natural killer cell activity

Correct answer: Progressive immunodeficiency due to CD4+ T cell depletion

HIV selectively destroys CD4+ T helper cells, causing the CD4:CD8 ratio to fall below normal (normal ~2:1); a ratio below 1.0 indicates significant immune compromise and disease progression.

Question 139: What is the principle of the ion-selective electrode used for measuring ionized calcium?

Amperometry using a platinum electrode
Coulometry using an electrolytic cell
Conductimetry measuring total ionic strength
Potentiometry using a calcium-selective membrane (Correct answer)

Correct answer: Potentiometry using a calcium-selective membrane

Ionized calcium is measured by potentiometry using an electrode with a calcium-selective membrane (typically containing a calcium-selective ionophore). The electrode generates a voltage proportional to the logarithm of ionized calcium activity in the specimen.

Question 140: Which vein is considered the preferred primary site for adult venipuncture and why?

Dorsal hand veins — they are the safest and most accessible
Median cubital vein — it is large, well-anchored, and has few nearby nerves and arteries (Correct answer)
Basilic vein — it is the largest and most accessible
Cephalic vein — it is most visible in all patients

Correct answer: Median cubital vein — it is large, well-anchored, and has few nearby nerves and arteries

The median cubital vein is the preferred first-choice venipuncture site because it is typically large, well-supported by subcutaneous tissue, well-anchored, and relatively distant from major arteries and nerves.

Question 141: A medical laboratory assistant receives an unlabeled tube of blood for a complete blood count (CBC). The requisition form is present and correctly filled out. What is the most appropriate immediate action?

Label the tube with the patient's information from the requisition and process the sample.
Reject the specimen and request a new, properly labeled sample be collected. (Correct answer)
Ask a coworker for their opinion on what to do with the specimen.
Process the sample and add a note to the report that the initial specimen was unlabeled.

Correct answer: Reject the specimen and request a new, properly labeled sample be collected.

Specimen integrity and correct patient identification are paramount for patient safety. An unlabeled specimen is a critical pre-analytical error that cannot be corrected after the fact. [23] The only acceptable action is to reject the specimen and notify the appropriate personnel to recollect a new, properly labeled sample to ensure the results are linked to the correct patient. [22]

Question 142: You are preparing a working solution of NaCl at 0.9% (w/v). How many grams of NaCl are needed to prepare 500 mL of this solution?

4.5 g (Correct answer)
0.9 g
45.0 g
9.0 g

Correct answer: 4.5 g

0.9% w/v means 0.9 g per 100 mL. For 500 mL: 0.9 g × (500/100) = 0.9 × 5 = 4.5 g.

Question 143: A post-transfusion DAT is positive with anti-IgG but negative with anti-C3d. The eluate contains anti-c. What type of reaction is this?

Autoimmune hemolytic anemia
Bacterial contamination
Delayed hemolytic transfusion reaction due to an anamnestic anti-c response (Correct answer)
Febrile non-hemolytic transfusion reaction

Correct answer: Delayed hemolytic transfusion reaction due to an anamnestic anti-c response

A positive post-transfusion DAT with anti-IgG and an eluate showing anti-c indicates a delayed hemolytic transfusion reaction. The patient was previously sensitized to the c antigen, and anti-c was undetectable at the time of the pre-transfusion antibody screen. Re-exposure to c-positive donor cells triggered an anamnestic response, producing anti-c that now coats the transfused cells.

Question 144: Using the formula: Clearance (mL/min) = (U × V) / P, where U = urine creatinine (8,800 μmol/L), V = urine volume per minute (1.0 mL/min), and P = plasma creatinine (88 μmol/L), calculate the creatinine clearance.

88 mL/min
8.8 mL/min
100 mL/min (Correct answer)
1000 mL/min

Correct answer: 100 mL/min

Clearance = (U × V) / P = (8,800 × 1.0) / 88 = 8,800 / 88 = 100 mL/min.

Question 145: Which specimen processing step is critical for recovery of Mycobacterium tuberculosis from sputum?

Digestion and decontamination with NALC-NaOH (Correct answer)
Filtration through a 0.22 µm membrane
Direct inoculation onto blood agar
Enrichment in thioglycollate broth

Correct answer: Digestion and decontamination with NALC-NaOH

Sputum specimens for mycobacterial culture require digestion and decontamination with N-acetyl-L-cysteine (NALC) as a mucolytic agent and sodium hydroxide (NaOH) to kill contaminating bacteria. This step is critical because mycobacteria grow slowly (2-8 weeks) and would be overgrown by faster-growing normal flora.

Question 146: A patient has prolonged PT and aPTT that both correct on mixing with normal plasma. Which condition is most likely?

Factor VIII inhibitor
Multiple factor deficiency (such as liver disease or DIC) (Correct answer)
Lupus anticoagulant
Antiphospholipid syndrome

Correct answer: Multiple factor deficiency (such as liver disease or DIC)

When both PT and aPTT are prolonged and correct on mixing, it indicates deficiency of one or more coagulation factors in both pathways. Common causes include liver disease (decreased synthesis), DIC (consumption), and vitamin K deficiency. Inhibitors would not correct on mixing study.

Question 147: What does the coefficient of variation (CV%) measure in laboratory analytical performance?

The acceptable range of analyte values in a healthy population
The systematic bias between the laboratory and a reference method
The degree of random variation in a method expressed as a percentage of the mean (Correct answer)
The difference between the highest and lowest QC values

Correct answer: The degree of random variation in a method expressed as a percentage of the mean

The CV% (coefficient of variation) expresses imprecision (random variation) as a percentage of the mean: CV% = (SD/Mean) × 100. Lower CV% indicates better precision.

Question 148: What is the clinical significance of an elevated serum lipase compared to amylase in suspected pancreatitis?

Lipase remains elevated longer and is more specific for pancreatic injury (Correct answer)
Amylase is always preferred over lipase
Lipase is less specific for pancreatic disease
Lipase is only elevated in chronic pancreatitis

Correct answer: Lipase remains elevated longer and is more specific for pancreatic injury

Serum lipase is more specific for pancreatic disease than amylase and remains elevated for a longer duration (up to 14 days vs 3-5 days for amylase). Many Canadian guidelines now recommend lipase as the preferred single test for diagnosing acute pancreatitis.

Question 149: What is Rh immune globulin (RhIg) and when is it administered?

A vaccine against Rh disease
An immunosuppressant for all pregnant women
An antibiotic given to Rh-positive mothers
Anti-D immunoglobulin given to Rh-negative mothers to prevent alloimmunization against D antigen (Correct answer)

Correct answer: Anti-D immunoglobulin given to Rh-negative mothers to prevent alloimmunization against D antigen

RhIg (WinRho, Rhogam) contains anti-D antibodies that destroy any fetal D-positive red cells in the mother's circulation before her immune system can respond. In Canada, it is given to Rh-negative mothers at 28 weeks gestation and within 72 hours after delivery of an Rh-positive baby, as well as after any potentially sensitizing event.

Question 150: What is the principle of the quantitative immunoglobulin measurement by nephelometry?

Separation of immunoglobulins by molecular weight before quantification
Measurement of enzyme activity after antibody-antigen complex formation
Detection of immunoglobulin gene rearrangements by PCR
Measurement of light scattered by antigen-antibody complexes to determine protein concentration (Correct answer)

Correct answer: Measurement of light scattered by antigen-antibody complexes to determine protein concentration

Nephelometry measures the intensity of laser light scattered at an angle by antigen-antibody complexes formed when patient immunoglobulins bind to specific antibody reagents. Scatter intensity is proportional to protein concentration.

Question 151: Which hereditary condition causes increased osmotic fragility of red blood cells?

Sickle cell disease
G6PD deficiency
Thalassemia
Hereditary spherocytosis (Correct answer)

Correct answer: Hereditary spherocytosis

Hereditary spherocytosis causes increased osmotic fragility because the spherical red blood cells have decreased surface-area-to-volume ratio and cannot swell as much before lysing in hypotonic solutions. The osmotic fragility test and eosin-5-maleimide (EMA) binding test are used to confirm the diagnosis.

MLPAO MLA/T Certification Exam

The MLPAO MLA/T certification exam tests medical laboratory assistants/technicians in clinical chemistry, hematology, microbiology, transfusion medicine, specimen collection, laboratory safety, and professional practice.

150

Questions

180 min

Time Limit

60%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds