Medical Laboratory Technician (MLT) Exam — Questions and Answers

Question 1: In an indirect antiglobulin test (IAT), what is the purpose of incubating patient serum with reagent red blood cells before adding antihuman globulin (AHG)?

To lyse antibody-coated red cells in vitro
To activate complement directly on the red cell surface
To allow antibodies in the patient's serum to coat the reagent red cells (Correct answer)
To detect IgM antibodies already bound to the patient's own red cells

Correct answer: To allow antibodies in the patient's serum to coat the reagent red cells

In the IAT, patient serum is incubated with reagent red cells so that any clinically significant antibodies present in the serum can sensitize (coat) those cells. AHG is then added to cross-link the bound antibody, producing visible agglutination.

Question 2: Which selective and differential medium is used to isolate Neisseria gonorrhoeae from specimens containing mixed flora?

Modified Thayer-Martin agar (Correct answer)
Mannitol salt agar
Hektoen enteric agar
Lowenstein-Jensen medium

Correct answer: Modified Thayer-Martin agar

Modified Thayer-Martin agar contains vancomycin, colistin, nystatin, and trimethoprim to suppress normal flora while supporting growth of pathogenic Neisseria.

Question 3: A laboratory records the following QC results for sodium: 139, 138, 141, 137, 140, 142, 138 mEq/L (mean=139, SD=1.7). The R-4s rule compares:

The current run mean to the cumulative mean over 30 days
Results from two different control levels to a single 2 SD limit
The highest and lowest results within a single run to the 4 SD range (Correct answer)
Consecutive control results from the same level to the ±2 SD range

Correct answer: The highest and lowest results within a single run to the 4 SD range

The R-4s rule is violated when the range between the highest and lowest QC result within one run exceeds 4 SD, indicating random error.

Question 4: When reviewing a Levey-Jennings chart for a quality control material, a technician notes that the last seven consecutive data points are all on the same side of the mean. This pattern is best described as a:

1_3s violation
Trend
Shift (Correct answer)
Random error

Correct answer: Shift

A 'shift' is a type of systematic error observed on a Levey-Jennings chart when six or more consecutive control values fall on the same side of the mean. This indicates an abrupt change in the testing system, such as a new lot of reagents or a change in instrument calibration.

Question 5: A chemistry analyzer reports a critically low sodium value of 118 mEq/L on a lipemic sample from a patient. The physician questions the result. Which pre-analytical error most likely accounts for a falsely low sodium by indirect ion-selective electrode (ISE) methodology?

Prolonged tourniquet time causing hemoconcentration
Incorrect reference range for the patient's age group
Specimen hemolysis releasing intracellular sodium
Pseudohyponatremia due to volume displacement by excess lipids (Correct answer)

Correct answer: Pseudohyponatremia due to volume displacement by excess lipids

Indirect ISE measures sodium in a diluted sample. In severe hyperlipidemia, lipids occupy plasma volume, so the aqueous phase (where sodium actually resides) is underrepresented after dilution, yielding falsely low sodium — pseudohyponatremia. Direct ISE or ultracentrifugation resolves this.

Question 6: A mixing study corrects a prolonged aPTT. What does this result indicate?

Factor inhibitor
Factor deficiency (Correct answer)
Heparin contamination
Presence of a lupus anticoagulant

Correct answer: Factor deficiency

Correction of a prolonged aPTT in a mixing study indicates a factor deficiency because the normal plasma supplies the missing factor.

Question 7: Mycotic keratitis is most likely linked to a Fusarium species. <br> A skin infection that commonly affects the feet and causes scaling and itching is called tinea pedis and is caused by the dermatophyte Trichophyton rubrum. Scedosporium apiospermum is commonly associated with sinusitis. Otitis externa is typically brought on by Aspergillus niger, and sinusitis may also be a side effect. <br> Which of the following species or organisms is the most likely to be the cause of mycotic keratitis (fungal eye infection)?

Trichophyton rubrum.
Scedosporium apiospermum
Fusarium species (Correct answer)
Aspergillus niger

Correct answer: Fusarium species

Fusarium species are well-established and common causes of mycotic keratitis, which is a fungal infection of the cornea. These fungi are ubiquitous in the environment and can cause infections, particularly after ocular trauma or contact lens use. The other options are associated with different types of fungal infections, as described in the question's preamble.

Question 8: The National Fire Protection Association (NFPA) 704 diamond provides a rapid visual representation of a chemical's hazards. What type of hazard is indicated by the blue quadrant?

Instability/Reactivity
Flammability
Special Hazard
Health (Correct answer)

Correct answer: Health

The NFPA 704 diamond is color-coded for specific hazards: the blue quadrant represents health hazards, red indicates flammability, yellow denotes instability (reactivity), and the white quadrant is used for special hazards (e.g., water-reactive, oxidizer).

Question 9: A peripheral blood smear from a patient with multiple myeloma is examined. Which of the following is the most characteristic red blood cell morphology seen in this condition?

Schistocytes
Spherocytes
Sickle cells
Rouleaux formation (Correct answer)

Correct answer: Rouleaux formation

Rouleaux formation, which appears as stacks of coins, is a classic finding in multiple myeloma. [19, 20] This is caused by increased plasma proteins, specifically immunoglobulins, which reduce the negative charge on the surface of red blood cells, allowing them to aggregate. [6, 20] Sickle cells are characteristic of sickle cell anemia, schistocytes indicate microangiopathic hemolytic anemia, and spherocytes are seen in hereditary spherocytosis and some autoimmune hemolytic anemias.

Question 10: Which serological test is considered the confirmatory test for HIV infection after a reactive screening immunoassay?

Western blot only
HIV-1/HIV-2 antibody differentiation immunoassay (Correct answer)
Monospot test
Rapid plasma reagin (RPR)

Correct answer: HIV-1/HIV-2 antibody differentiation immunoassay

Current CDC-recommended algorithms use an HIV-1/HIV-2 antibody differentiation immunoassay as the supplemental test following a reactive initial immunoassay.

Question 11: A newborn with recurrent bacterial infections, absent tonsils, very low B cells, and very low immunoglobulins most likely has:

Severe combined immunodeficiency
X-linked agammaglobulinemia (Bruton's) (Correct answer)
DiGeorge syndrome
Common variable immunodeficiency

Correct answer: X-linked agammaglobulinemia (Bruton's)

X-linked agammaglobulinemia is caused by BTK gene mutation, resulting in failure of B cell maturation and absent immunoglobulins in males.

Question 12: What does the acronym RACE stand for in laboratory fire emergency response?

Rescue, Alarm, Contain, Extinguish (Correct answer)
Rescue, Alert, Call, Exit
Run, Alert, Contain, Evacuate
Remove, Activate, Close, Evacuate

Correct answer: Rescue, Alarm, Contain, Extinguish

RACE stands for Rescue, Alarm, Contain, Extinguish and provides a standardized sequence for responding to fire emergencies.

Question 13: A technologist performing an elution notices the eluate reacts with all panel cells. The MOST likely cause is:

ABO incompatibility
An alloantibody to a high-frequency antigen
A warm autoantibody coating the red cells (Correct answer)
A cold autoantibody

Correct answer: A warm autoantibody coating the red cells

A panreactive eluate is classic for warm autoimmune hemolytic anemia (WAIHA), where autoantibody eluted from the patient's cells reacts with all test cells.

Question 14: A physician orders a creatinine clearance test to evaluate a patient's kidney function. The following results are obtained: - Serum creatinine: 1.5 mg/dL - Urine creatinine: 120 mg/dL - Urine volume: 1440 mL/24 hours - Body Surface Area (BSA): 1.73 m² Using the standard formula, what is the calculated creatinine clearance in mL/min?

60 mL/min
100 mL/min
80 mL/min (Correct answer)
120 mL/min

Correct answer: 80 mL/min

The formula for creatinine clearance is: (Urine Creatinine x Urine Volume) / (Serum Creatinine x Time in minutes). First, convert the 24-hour urine volume to mL/min: 1440 mL / 1440 min = 1 mL/min. Then, apply the formula: (120 mg/dL * 1 mL/min) / 1.5 mg/dL = 80 mL/min. Since the patient's BSA is the standard 1.73 m², no correction is needed.

Question 15: In immunofluorescence testing for ANA, a homogeneous (diffuse) pattern is most commonly associated with antibodies against:

Centromere proteins
SS-A (Ro)
Sm antigen
dsDNA and histones (Correct answer)

Correct answer: dsDNA and histones

A homogeneous ANA pattern reflects antibodies to dsDNA and histones that bind uniformly throughout the nucleus.

Question 16: Gel electrophoresis separates DNA fragments based on:

Degree of methylation
GC content
Fragment size (number of base pairs) (Correct answer)
Molecular weight and charge

Correct answer: Fragment size (number of base pairs)

In agarose gel electrophoresis, DNA fragments migrate through the gel matrix under an electric field; smaller fragments migrate faster and farther, separating fragments by size (base pairs).

Question 17: A patient's blood glucose level is 250 mg/dL with ketonuria present. Which condition is most likely?

Addison disease
Diabetic ketoacidosis (Correct answer)
Cushing syndrome
Hypoglycemia

Correct answer: Diabetic ketoacidosis

Elevated blood glucose combined with ketonuria is characteristic of diabetic ketoacidosis.

Question 18: Human chorionic gonadotropin (hCG) testing is most frequently used to identify pregnancies, but it can also be used as a diagnostic marker for which conditions?

Testicular cancer (Correct answer)
Penile cancer
Prostate cancer
Vaginal cancer

Correct answer: Testicular cancer

While primarily known for detecting pregnancy, human chorionic gonadotropin (hCG) also serves as a crucial tumor marker. Elevated levels of hCG can be produced by certain germ cell tumors, most notably testicular cancer. Monitoring hCG levels is essential for the diagnosis, staging, and assessment of treatment response in these malignancies.

Question 19: Which anticoagulant is preferred for routine coagulation testing such as PT and aPTT?

Sodium heparin
Potassium oxalate
EDTA
3.2% sodium citrate (Correct answer)

Correct answer: 3.2% sodium citrate

Sodium citrate at 3.2% concentration is the standard anticoagulant for coagulation studies because it reversibly binds calcium.

Question 20: A positive tuberculin (PPD) skin test reaction is read at 48–72 hours and is an example of which immune mechanism?

IgE-mediated degranulation
T cell–mediated delayed hypersensitivity (Correct answer)
Complement-mediated lysis
Immune complex deposition

Correct answer: T cell–mediated delayed hypersensitivity

PPD testing relies on Type IV delayed hypersensitivity; sensitized CD4+ T cells release cytokines causing induration at the injection site.

Question 21: Which staining technique is used to identify acid-fast bacilli such as Mycobacterium tuberculosis?

Wright-Giemsa stain
Ziehl-Neelsen stain (Correct answer)
Gram stain
India ink preparation

Correct answer: Ziehl-Neelsen stain

The Ziehl-Neelsen (carbol fuchsin) stain uses heat to drive the dye into the waxy mycolic acid cell wall, making acid-fast bacilli appear red against a blue background.

Question 22: A physician orders a trough level for vancomycin, a therapeutic drug. When is the appropriate time to collect the blood specimen for this test?

Immediately after the intravenous dose is complete
Up to 30 minutes before the next scheduled dose (Correct answer)
At a random time between doses
60 minutes after the intravenous dose is complete

Correct answer: Up to 30 minutes before the next scheduled dose

A trough level represents the lowest concentration of a drug in the bloodstream before the next dose is administered. To accurately measure this, the sample should be drawn immediately before (up to 30 minutes prior to) the next dose.

Question 23: A unit of Red Blood Cells is issued from the blood bank at 08:00 for a routine transfusion. At 08:20, the nurse calls to report that the patient's IV has failed and the transfusion has not been started. The unit has been stored in a transport cooler with appropriate coolant packs. What is the correct course of action?

Tell the nurse to keep the unit at the bedside until a new IV is established, as long as it is within 4 hours.
Return the unit to the blood bank immediately for proper storage. (Correct answer)
Begin the transfusion as soon as a new IV is started, regardless of the time.
Discard the unit immediately because it has been out of the blood bank for over 15 minutes.

Correct answer: Return the unit to the blood bank immediately for proper storage.

According to AABB Standards, a blood component that has been issued but not transfused can be returned to the blood bank for reissue only if it has not been warmed above 10°C or cooled below 1°C during storage and transport. Since the unit was not spiked and was maintained at the correct temperature in a validated cooler, it can be immediately returned to the blood bank's monitored refrigerator. The 30-minute rule applies to units kept at room temperature without a validated cooling system.

Question 24: What does a positive D-dimer result indicate in the context of coagulation testing?

Vitamin K deficiency
Platelet activation disorder
Active fibrinolysis of cross-linked fibrin (Correct answer)
Primary fibrinogenolysis

Correct answer: Active fibrinolysis of cross-linked fibrin

D-dimer is a specific degradation product of cross-linked fibrin, indicating that both thrombin generation and plasmin-mediated fibrinolysis have occurred.

Question 25: An elevated D-dimer test is most clinically significant for which of the following applications?

Confirming a diagnosis of Deep Vein Thrombosis (DVT)
Monitoring heparin therapy effectiveness
Diagnosing Hemophilia A
Ruling out venous thromboembolism (VTE) in a low-probability patient (Correct answer)

Correct answer: Ruling out venous thromboembolism (VTE) in a low-probability patient

The D-dimer test measures a specific fibrin degradation product. It has a high negative predictive value, meaning a normal result makes a venous thromboembolism (like DVT or pulmonary embolism) highly unlikely. However, it has low specificity, as many other conditions can cause an elevated level. Therefore, its primary clinical utility is to rule out VTE in patients with a low pretest probability.

Question 26: What does the coefficient of variation (CV) measure in laboratory quality control?

The difference between the highest and lowest control values
The total number of outlier results in a given month
The relative standard deviation expressed as a percentage of the mean (Correct answer)
The percentage of results that fall outside 2 standard deviations

Correct answer: The relative standard deviation expressed as a percentage of the mean

The coefficient of variation expresses the standard deviation as a percentage of the mean, allowing comparison of precision across different concentration levels.

Question 27: Which type of fire extinguisher is appropriate for a Class B fire involving flammable liquids such as ethanol or acetone in a laboratory?

Class D dry powder extinguisher
Class A water extinguisher
Class C carbon dioxide extinguisher only
Class ABC dry chemical or Class BC carbon dioxide extinguisher (Correct answer)

Correct answer: Class ABC dry chemical or Class BC carbon dioxide extinguisher

Class B fires involve flammable liquids. A Class ABC dry chemical extinguisher or a Class BC carbon dioxide (CO₂) extinguisher are appropriate for these fires. A water extinguisher (Class A) can spread flammable liquids, and a Class D extinguisher is reserved for combustible metals.

Question 28: In the uricase (enzymatic) method for measuring uric acid in clinical chemistry, what is the direct product detected to quantify uric acid concentration?

Hydrogen peroxide, which reacts with a chromogen via peroxidase to produce a colored product (Correct answer)
Allantoin measured directly by spectrophotometry at 293 nm
Ammonia produced from nitrogen-containing ring cleavage
Carbon dioxide released during uric acid oxidation

Correct answer: Hydrogen peroxide, which reacts with a chromogen via peroxidase to produce a colored product

Uricase oxidizes uric acid to allantoin and hydrogen peroxide. The H2O2 produced then reacts with a chromogenic oxygen acceptor in the presence of peroxidase (Trinder reaction) to generate a colored compound measured photometrically, providing a specific and sensitive assay.

Question 29: What is the principle behind the Jaffe reaction used in clinical chemistry laboratories?

Urea is hydrolyzed by urease
Bilirubin reacts with diazo reagent
Creatinine reacts with alkaline picrate to form a red-orange complex (Correct answer)
Glucose is oxidized by glucose oxidase

Correct answer: Creatinine reacts with alkaline picrate to form a red-orange complex

The Jaffe reaction measures creatinine by forming a red-orange chromogen when creatinine reacts with picric acid in an alkaline solution.

Question 30: Which class of fire extinguisher is appropriate for electrical equipment fires in a clinical laboratory?

Class A
Class D
Class C (Correct answer)
Class B

Correct answer: Class C

Class C fire extinguishers are designed for electrical equipment fires and do not conduct electricity back to the user.

Question 31: Which blood type is considered the universal plasma donor?

O
B
A
AB (Correct answer)

Correct answer: AB

Type AB plasma lacks both anti-A and anti-B antibodies, making it safe for transfusion to any recipient.

Question 32: When applying the albumin-adjusted calcium formula in clinical chemistry to correct total calcium for hypoalbuminemia, how much is added to the measured total calcium for each 1 g/dL that serum albumin falls below 4 g/dL?

0.4 mg/dL
2.0 mg/dL
1.2 mg/dL
0.8 mg/dL (Correct answer)

Correct answer: 0.8 mg/dL

Approximately 40–45% of serum calcium is protein-bound, primarily to albumin. The standard correction formula adds 0.8 mg/dL to total calcium for every 1 g/dL decrease in albumin below the reference value of 4 g/dL, estimating what total calcium would be under normal albumin conditions.

Question 33: Which cell type is the primary producer of IgE antibodies in allergic responses?

Mast cells
NK cells
Eosinophils
Plasma cells derived from B lymphocytes (Correct answer)

Correct answer: Plasma cells derived from B lymphocytes

IgE is secreted by plasma cells (terminally differentiated B cells) after class-switching driven by IL-4 and IL-13.

Question 34: Which of the following cardiac markers is the most specific for myocardial infarction and remains elevated for the longest duration after the event?

Troponin I (Correct answer)
Myoglobin
AST
CK-MB

Correct answer: Troponin I

Troponin I is a protein that is highly specific to cardiac muscle. Following a myocardial infarction (heart attack), its levels rise within 3-6 hours, peak at 12-24 hours, and can remain elevated for 7-14 days. CK-MB and myoglobin rise earlier but are less specific and return to normal more quickly. AST is an older, non-specific marker for cardiac damage.

Question 35: A QC chart shows seven consecutive control values all falling on the same side of the mean. Which Westgard rule does this pattern violate?

10x rule (Correct answer)
1-3s rule
R-4s rule
2-2s rule

Correct answer: 10x rule

The 10x rule is triggered when ten consecutive control measurements fall on the same side of the mean, indicating a systematic shift or bias in the method. Seven consecutive points on one side is an early warning of the same trend, and the 10x rule specifically addresses this systematic error pattern.

Question 36: A post-vasectomy semen analysis is performed. The initial wet mount examination reveals no spermatozoa. What is the mandatory next step to confirm this finding?

Perform a sperm viability stain.
Report the result as azoospermic.
Centrifuge the specimen and examine the pellet microscopically. (Correct answer)
Request a new sample collected after a longer abstinence period.

Correct answer: Centrifuge the specimen and examine the pellet microscopically.

To confirm azoospermia in a post-vasectomy sample, the specimen must be centrifuged at a high speed to concentrate any potential sperm, and the resulting pellet must be carefully examined. Reporting azoospermia based only on an initial wet mount is insufficient, as a very low number of non-motile sperm could be missed.

Question 37: In laboratory quality management, 'total allowable error' (TEa) defines:

The maximum difference between two QC levels
The maximum error acceptable for a test to be clinically useful (Correct answer)
The SD limit beyond which an instrument must be serviced
The number of errors permitted per 1,000 patient samples

Correct answer: The maximum error acceptable for a test to be clinically useful

TEa is the maximum permissible combination of imprecision and inaccuracy for a test result to remain clinically meaningful.

Question 38: A wound culture from a diabetic foot ulcer grows a Gram-positive coccus in clusters that tests positive for coagulase. The isolate is resistant to oxacillin. What is the most appropriate identification?

Staphylococcus epidermidis
Methicillin-resistant Staphylococcus aureus (MRSA) (Correct answer)
Enterococcus faecalis
Streptococcus pyogenes

Correct answer: Methicillin-resistant Staphylococcus aureus (MRSA)

Coagulase-positive Gram-positive cocci in clusters are Staphylococcus aureus. Oxacillin resistance defines MRSA, which is clinically significant and requires contact precautions and specific antibiotic management.

Question 39: During ABO blood typing, a patient's forward type shows agglutination with anti-B reagent only, and the reverse type shows agglutination with A1 cells only. What is the patient's blood type?

Type O
Type B (Correct answer)
Type A
Type AB

Correct answer: Type B

Agglutination with anti-B in forward typing indicates B antigen on red cells, and agglutination with A1 cells in reverse typing confirms anti-A in the serum, consistent with type B.

Question 40: A 19-year-old college student presents with fatigue, sore throat, and lymphadenopathy. A monospot test for heterophile antibodies is positive. This result is most consistent with an acute infection caused by which of the following viruses?

Rubella virus
Cytomegalovirus (CMV)
Varicella-zoster virus (VZV)
Epstein-Barr virus (EBV) (Correct answer)

Correct answer: Epstein-Barr virus (EBV)

Infectious mononucleosis is most commonly caused by the Epstein-Barr virus (EBV). EBV infection induces the production of heterophile antibodies, which are detected by rapid monospot tests. While other viruses like CMV can cause a mononucleosis-like illness, they are typically associated with a negative heterophile antibody test.

Question 41: In nephelometry, the measured signal is:

Fluorescence emission after excitation
Optical density at 450 nm
Light scattered at an angle from the incident beam (Correct answer)
Absorbance of transmitted light

Correct answer: Light scattered at an angle from the incident beam

Nephelometry measures light scattered by antigen-antibody complexes at a fixed angle, with scatter intensity proportional to complex concentration.

Question 42: During ABO blood grouping, a patient's red cells react with anti-A but not anti-B, while the patient's serum agglutinates B cells but not A cells. What blood type does this confirm?

Type AB
Type A (Correct answer)
Type B
Type O

Correct answer: Type A

ABO typing uses forward (cell) and reverse (serum) grouping. Cells reacting with anti-A only indicates A antigen is present. The serum agglutinating B cells confirms the presence of anti-B antibody, consistent with blood type A. Both results must agree before reporting.

Question 43: Which biochemical test differentiates Staphylococcus aureus from coagulase-negative staphylococci?

Coagulase test (Correct answer)
Catalase test
Bile esculin test
Oxidase test

Correct answer: Coagulase test

The coagulase test detects the enzyme that clots plasma and is the primary test used to distinguish S. aureus from other staphylococcal species.

Question 44: A distribution on one side of the mean of six or more consecutive daily values that maintain a constant level is referred to as a distribution.

Shift (Correct answer)
Normal distribution curve
Trend
Mean deviation curve

Correct answer: Shift

In quality control, a 'shift' refers to a sudden and sustained change in the mean of a quality control material, where six or more consecutive daily values fall on one side of the established mean. This indicates a systematic error in the analytical process, such as a calibration issue or a change in reagent lot. It requires immediate investigation and corrective action to restore accuracy.

Question 45: Which staining technique is most appropriate for identifying Mycobacterium tuberculosis in a sputum specimen?

Ziehl-Neelsen acid-fast stain (Correct answer)
India ink preparation
Lactophenol cotton blue
Gram stain

Correct answer: Ziehl-Neelsen acid-fast stain

The Ziehl-Neelsen stain uses carbol fuchsin with heat to penetrate the waxy mycolic acid cell wall, rendering acid-fast bacilli red against a blue background.

Question 46: A patient presents with watery diarrhea after recent antibiotic therapy. Which organism is most likely responsible and requires anaerobic culture on selective media?

Salmonella enteritidis
Vibrio cholerae
Campylobacter jejuni
Clostridioides difficile (Correct answer)

Correct answer: Clostridioides difficile

C. difficile is the leading cause of antibiotic-associated diarrhea and is detected using anaerobic culture on cycloserine-cefoxitin-fructose agar or toxin assays.

Question 47: A patient's blood gas results are as follows: pH = 7.25, pCO2 = 60 mmHg, HCO3- = 24 mEq/L. How would you classify this acid-base disturbance?

Respiratory Alkalosis
Metabolic Acidosis
Metabolic Alkalosis
Respiratory Acidosis (Correct answer)

Correct answer: Respiratory Acidosis

The pH is below the normal range (7.35-7.45), indicating acidosis. The pCO2 is elevated (normal range 35-45 mmHg), which is the respiratory component. The HCO3- is within the normal range (22-26 mEq/L). Therefore, the primary disturbance is respiratory acidosis, as the high level of CO2 (an acid) is not being compensated for by the kidneys (metabolic component).

Question 48: During a peritoneal fluid analysis, a milky white appearance is noted. Which analyte should be measured first to investigate this finding?

Total protein
Glucose
Amylase
Triglycerides (Correct answer)

Correct answer: Triglycerides

A milky white (chylous) peritoneal effusion strongly suggests the presence of chyle from disrupted lymphatic vessels. Triglyceride measurement is the primary test; a level above 110 mg/dL confirms a chylous effusion.

Question 49: A blood sample from a 28-year-old, Rh-negative female who is 28 weeks pregnant shows a positive antibody screen. An antibody panel is performed, and the technologist identifies anti-D. What is the most likely reason for this finding?

The patient is experiencing a delayed hemolytic transfusion reaction.
The patient has formed an autoantibody.
The patient has a previously unidentified subgroup of Rh.
The patient received a routine antenatal dose of Rh Immune Globulin (RhIG). (Correct answer)

Correct answer: The patient received a routine antenatal dose of Rh Immune Globulin (RhIG).

Rh Immune Globulin (RhIG) is a concentrated solution of IgG anti-D, given to non-sensitized Rh-negative mothers at approximately 28 weeks gestation to prevent immunization to the D antigen. This passively administered anti-D will cause the antibody screen to be positive. While the other options are possible causes for a positive antibody screen, the patient's specific history (Rh-negative, 28 weeks pregnant) makes the recent administration of RhIG the most probable cause.

Question 50: A Levey-Jennings chart shows a series of 6 consecutive QC results trending upward across the mean. What rule does this violate?

1-2s rule
1-3s rule
R-4s rule
10-x rule (Correct answer)

Correct answer: 10-x rule

The 10-x rule is violated when 10 consecutive results fall on the same side of the mean or show a progressive trend.

Question 51: What is the principle behind nephelometry as used in clinical immunology laboratories?

Measurement of light scattered by antigen-antibody complexes in solution (Correct answer)
Detection of fluorescent-labeled antibodies on cell surfaces
Quantification of radioactive isotope decay from labeled antigens
Measurement of light absorbed by colored enzyme substrates

Correct answer: Measurement of light scattered by antigen-antibody complexes in solution

Nephelometry measures the intensity of light scattered by immune complexes formed in solution to quantify specific proteins.

Question 52: What is the primary purpose of a laboratory's Chemical Hygiene Plan as required by OSHA?

To define quality control protocols for chemical reagents
To outline emergency evacuation routes for laboratory staff
To protect employees from health hazards associated with hazardous chemicals in the laboratory (Correct answer)
To establish proper waste disposal procedures for biological materials

Correct answer: To protect employees from health hazards associated with hazardous chemicals in the laboratory

The Chemical Hygiene Plan, mandated by OSHA's Laboratory Standard (29 CFR 1910.1450), is designed to protect laboratory employees from the health hazards of working with hazardous chemicals.

Question 53: Which electrolyte imbalance is most commonly associated with hemolyzed blood specimens?

Falsely elevated calcium
Falsely decreased sodium
Falsely elevated potassium (Correct answer)
Falsely decreased chloride

Correct answer: Falsely elevated potassium

Hemolysis releases intracellular potassium into the serum, causing a falsely elevated potassium result.

Question 54: A technician receives a vaginal swab and must culture for Neisseria gonorrhoeae. Which combination of media and incubation conditions is most appropriate?

Columbia CNA agar at 37°C anaerobically
Thayer-Martin agar at 35-37°C in 5% CO2 (Correct answer)
MacConkey agar at 37°C in ambient air
Chocolate agar at 42°C in microaerophilic conditions

Correct answer: Thayer-Martin agar at 35-37°C in 5% CO2

Neisseria gonorrhoeae requires enriched, selective media. Thayer-Martin agar contains vancomycin, colistin, and nystatin to suppress normal flora while supporting gonococcal growth. Incubation at 35-37°C with 5% CO2 (capnophilic conditions) is essential for primary isolation.

Question 55: Which culture medium is both selective and differential, used to isolate gram-negative enteric organisms while distinguishing lactose fermenters from non-fermenters?

MacConkey agar (Correct answer)
Thayer-Martin agar
Chocolate agar
Blood agar

Correct answer: MacConkey agar

MacConkey agar contains crystal violet and bile salts that inhibit gram-positive organisms (selective) and lactose with pH indicator neutral red that turns colonies pink-red when lactose is fermented (differential). Non-fermenters such as Salmonella and Shigella appear colorless.

Question 56: A complete blood count reveals WBC 95 × 10⁹/L with 85% lymphocytes, many of which appear small and mature with scant cytoplasm and smudge cells on smear. RBC and platelets are mildly reduced. Which diagnosis is most likely?

Acute lymphoblastic leukemia (ALL)
Chronic lymphocytic leukemia (CLL) (Correct answer)
Infectious mononucleosis
Hairy cell leukemia

Correct answer: Chronic lymphocytic leukemia (CLL)

CLL is characterized by a marked lymphocytosis of small, mature-appearing lymphocytes and is the most common adult leukemia. Smudge cells (ruptured lymphocytes during smear preparation due to fragile cytoplasm) are a hallmark finding. ALL typically presents with blasts, not mature-appearing cells.

Question 57: A laboratory is validating a new chemistry analyzer. Which parameter assesses the agreement between the new method and the existing reference method?

Accuracy
Precision
Linearity
Method comparison (Correct answer)

Correct answer: Method comparison

Method comparison studies evaluate the agreement between a new analyzer and an established reference method by testing patient samples on both systems.

Question 58: What is the purpose of adding anti-human globulin (AHG) reagent in the indirect antiglobulin test (IAT)?

To lyse sensitized red blood cells directly
To enhance IgM antibody binding at room temperature
To detect IgG antibodies that have bound to red blood cells during in vitro incubation (Correct answer)
To neutralize complement in the test system

Correct answer: To detect IgG antibodies that have bound to red blood cells during in vitro incubation

AHG crosslinks IgG molecules coating the red blood cells, causing visible agglutination that confirms antibody binding during incubation.

Question 59: A new lot of QC material is being validated. The laboratory should establish the mean and SD by running the QC material at least:

5 times over 1 day
20 times over multiple days (Correct answer)
10 times over 2 days
3 times on consecutive days

Correct answer: 20 times over multiple days

At least 20 replicates run over multiple days are recommended to establish reliable QC mean and SD values.

Question 60: A patient types as group O with anti-A and anti-B but shows a weak forward reaction with anti-A,B reagent. The most likely explanation is:

Acquired B antigen
A subgroup such as Ax (Correct answer)
Bombay phenotype
Cold autoantibody interference

Correct answer: A subgroup such as Ax

Weak A subgroups (Ax, Aend) may not react with individual anti-A but can react with the cross-reacting anti-A,B reagent, revealing residual A antigen.

Question 61: Massive transfusion is generally defined as transfusion of:

More than 2 units of RBCs in 24 hours
Any transfusion requiring platelet support
10 or more units of RBCs within 24 hours (or one blood volume) (Correct answer)
More than 5 units of FFP

Correct answer: 10 or more units of RBCs within 24 hours (or one blood volume)

Massive transfusion is defined as replacement of one entire blood volume (approximately 10 units of RBCs) within 24 hours in an adult.

Question 62: Given the following patient data, calculate the Mean Corpuscular Hemoglobin (MCH): Hemoglobin: 15 g/dL RBC Count: 5.0 x 10^12/L Hematocrit: 45%

90 fL
30 pg (Correct answer)
33.3 g/dL
10 g/dL

Correct answer: 30 pg

The formula for MCH is (Hemoglobin x 10) / RBC Count (in millions/µL). The RBC count of 5.0 x 10^12/L is equivalent to 5.0 million/µL. Therefore, MCH = (15 x 10) / 5.0 = 30 pg.

Question 63: Which of the following disorders is a symptom of hypernatremia?

Vomiting
Severe burns (Correct answer)
Renal failure
Potassium deficiency

Correct answer: Severe burns

Hypernatremia, an elevated sodium concentration in the blood, often results from conditions causing significant water loss in excess of sodium. Severe burns lead to extensive fluid loss through damaged skin, which is primarily water. This disproportionate loss of water concentrates the remaining sodium in the extracellular fluid, thereby causing hypernatremia.

Question 64: What is a molecular beacon probe in real-time PCR?

A protein probe that binds DNA
A linear probe that binds to the amplicon
A radioactively labeled DNA probe
A hairpin-shaped probe with a fluorophore and quencher that fluoresces when hybridized (Correct answer)

Correct answer: A hairpin-shaped probe with a fluorophore and quencher that fluoresces when hybridized

Molecular beacons are hairpin-shaped oligonucleotides with a fluorophore at one end and a quencher at the other; when they hybridize to their target, the hairpin opens and fluorescence is emitted.

Question 65: What principle does an enzyme-linked immunosorbent assay (ELISA) use to detect the presence of an analyte in a sample?

Latex particles agglutinate in the presence of specific antibodies
Radiolabeled antigens compete for binding sites on a solid phase
Complement fixation causes red blood cell lysis
Enzyme-conjugated antibodies produce a measurable color change upon substrate addition (Correct answer)

Correct answer: Enzyme-conjugated antibodies produce a measurable color change upon substrate addition

ELISA uses enzyme-labeled antibodies that convert a chromogenic substrate into a colored product, with intensity proportional to the analyte concentration.

Question 66: Which anticoagulant is found in a lavender-top blood collection tube?

Heparin
EDTA (Correct answer)
Potassium oxalate
Sodium citrate

Correct answer: EDTA

Lavender-top tubes contain EDTA, which is the preferred anticoagulant for complete blood count testing.

Question 67: During pretransfusion testing, a technologist detects a mixed-field agglutination pattern when testing a patient's cells with anti-A serum. The patient's medical history notes a recent bone marrow transplant from a group O donor. What is the most likely explanation?

The reagent anti-A has deteriorated and should be replaced
Engraftment of donor O cells is producing a mixed population of A and O red cells (Correct answer)
The patient has a weak A subgroup such as A3
The mixed-field pattern indicates a positive DAT

Correct answer: Engraftment of donor O cells is producing a mixed population of A and O red cells

Post-bone marrow transplant patients often show mixed-field agglutination due to chimerism—a coexisting population of recipient (group A) and donor (group O) red cells in circulation during engraftment. This is expected and should be correlated with the transplant history rather than attributed to a subgroup or reagent failure.

Question 68: A patient's prothrombin time (PT) is significantly prolonged, while the activated partial thromboplastin time (aPTT) is normal. A deficiency in which of the following coagulation factors would most likely explain these results?

Factor IX
Factor XI
Factor VII (Correct answer)
Factor VIII

Correct answer: Factor VII

The prothrombin time (PT) evaluates the extrinsic and common pathways of the coagulation cascade. Factor VII is unique to the extrinsic pathway. Therefore, an isolated prolongation of the PT points to a deficiency in Factor VII. [8] Factors VIII, IX, and XI are part of the intrinsic pathway, and deficiencies in these factors would prolong the aPTT.

Question 69: A patient presents with recurrent Neisseria infections. Which complement component deficiency is most likely?

C1 esterase inhibitor
C3
C5-C9 (membrane attack complex) (Correct answer)
Factor B

Correct answer: C5-C9 (membrane attack complex)

Deficiencies in terminal complement components C5-C9 are strongly associated with recurrent Neisseria infections due to impaired bactericidal activity.

Question 70: A sputum culture from an immunocompromised patient grows a mold with septate hyphae that branch at 45-degree angles. Conidiophores bear chains of conidia from a single point. What is the most likely identification?

Aspergillus fumigatus (Correct answer)
Mucor species
Fusarium species
Rhizopus species

Correct answer: Aspergillus fumigatus

Aspergillus fumigatus produces septate hyphae with characteristic 45-degree branching. Its conidiophores terminate in a flask-shaped vesicle bearing phialides that produce chains of conidia. Rhizopus and Mucor have non-septate (coenocytic) hyphae.

Question 71: What autoimmune disease has elevated titers of double-stranded DNA (dsDNA) antibodies?

SLE (Correct answer)
Scleroderma
Polymyositis
CREST syndrome

Correct answer: SLE

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease characterized by the production of various autoantibodies. Elevated titers of double-stranded DNA (dsDNA) antibodies are highly specific for SLE and are considered a diagnostic criterion. These antibodies play a pathogenic role in the disease, contributing to kidney damage (lupus nephritis) and other organ manifestations.

Question 72: Which atmospheric condition is required for primary isolation of Campylobacter jejuni from stool specimens?

Increased CO2 (5-10%) only
Strict anaerobic
Ambient air at 25 degrees C
Microaerophilic (5% O2, 10% CO2) (Correct answer)

Correct answer: Microaerophilic (5% O2, 10% CO2)

Campylobacter jejuni requires a microaerophilic environment with reduced oxygen and elevated CO2, typically incubated at 42 degrees C on selective media.

Question 73: A urine dipstick is strongly positive for blood, but microscopic examination reveals no red blood cells. Which of the following conditions best explains this discrepancy?

Urinary tract infection
Renal calculi
Diabetic nephropathy
Myoglobinuria from rhabdomyolysis (Correct answer)

Correct answer: Myoglobinuria from rhabdomyolysis

The dipstick blood reaction detects heme, so it is positive for both hemoglobin and myoglobin. In rhabdomyolysis, myoglobin released from damaged muscle is excreted in urine and gives a positive dipstick reaction without intact red blood cells being present.

Question 74: A patient's blood smear shows hypersegmented neutrophils with macro-ovalocytes. Which vitamin deficiency is most likely responsible for these findings?

Vitamin K deficiency
Vitamin B12 or folate deficiency (Correct answer)
Vitamin C deficiency
Iron deficiency

Correct answer: Vitamin B12 or folate deficiency

Hypersegmented neutrophils and macro-ovalocytes are hallmark findings of megaloblastic anemia caused by vitamin B12 or folate deficiency.

Question 75: Which coagulation factor is measured exclusively by the prothrombin time (PT) and not the activated partial thromboplastin time (aPTT)?

Factor V
Factor VII (Correct answer)
Factor II
Factor X

Correct answer: Factor VII

Factor VII is unique to the extrinsic pathway and is evaluated only by the PT.

Question 76: A patient is prescribed daily low-dose aspirin for the prevention of cardiovascular events. Aspirin impairs hemostasis by inhibiting the function of which of the following?

Vitamin K-dependent factors
Thrombin
Fibrinogen
Platelets (Correct answer)

Correct answer: Platelets

Aspirin works by irreversibly inhibiting the cyclooxygenase-1 (COX-1) enzyme within platelets. [12] This action blocks the production of thromboxane A2, a potent platelet agonist, thereby reducing platelet aggregation and the formation of a platelet plug. [12] This effect lasts for the entire lifespan of the platelet.

Question 77: A Direct Antiglobulin Test (DAT) is performed to detect which of the following?

Antigens on the patient's red blood cells
Unexpected antibodies in the patient's serum
In-vivo sensitization of red blood cells with antibodies or complement (Correct answer)
In-vitro sensitization of reagent red blood cells

Correct answer: In-vivo sensitization of red blood cells with antibodies or complement

The Direct Antiglobulin Test (DAT), or Direct Coombs test, is used to detect red blood cells that have been sensitized with antibodies or complement in the body (in-vivo). This is a key test in the investigation of hemolytic transfusion reactions, hemolytic disease of the fetus and newborn (HDFN), and autoimmune hemolytic anemias. The Indirect Antiglobulin Test (IAT) is used to detect unexpected antibodies in patient serum (in-vitro sensitization).

Question 78: A urine specimen tested with a reagent strip shows a positive nitrite result but negative leukocyte esterase. What is the most appropriate interpretation?

The patient has a viral urinary tract infection
The result is invalid and testing should be repeated
Bacteriuria may be present, likely from gram-negative organisms (Correct answer)
Contamination has occurred and the specimen should be recollected

Correct answer: Bacteriuria may be present, likely from gram-negative organisms

A positive nitrite indicates bacteria capable of reducing nitrate to nitrite, which are typically gram-negative organisms, even when leukocyte esterase is negative.

Question 79: Which of the following white blood cell types is the FIRST to respond to an acute bacterial infection?

Monocytes
Neutrophils (Correct answer)
Lymphocytes
Eosinophils

Correct answer: Neutrophils

Neutrophils are the primary first-responders in acute bacterial infections. They are phagocytic cells that rapidly migrate to sites of infection, and a left shift (increase in band neutrophils) is a classic laboratory finding.

Question 80: Which of the following is a key requirement of the OSHA Bloodborne Pathogens Standard that employers must provide to at-risk laboratory employees?

Annual proficiency testing for all performed tests.
The Hepatitis B vaccine at no cost to the employee. (Correct answer)
A detailed Chemical Hygiene Plan for the laboratory.
Classification of all laboratory tests into complexity categories.

Correct answer: The Hepatitis B vaccine at no cost to the employee.

The OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030) mandates that employers must make the Hepatitis B vaccination series available, free of charge, to all employees who have occupational exposure to blood or other potentially infectious materials. The Chemical Hygiene Plan is required by the OSHA Laboratory Standard, while proficiency testing and test complexity are governed by CLIA.

Question 81: According to AABB Standards, the minimum hemoglobin content in a unit of packed red blood cells must be at least:

60 g per unit
45 g per unit
51 g per unit (Correct answer)
70 g per unit

Correct answer: 51 g per unit

AABB Standards require ≥51 g of hemoglobin per RBC unit (≥80% of units tested) to ensure adequate therapeutic content.

Question 82: In flow cytometry, fluorochromes are excited by which energy source?

Laser beam (Correct answer)
Ultraviolet lamp
Radioactive isotope
Chemiluminescent substrate

Correct answer: Laser beam

Flow cytometers use one or more lasers to excite fluorochromes conjugated to antibodies, and detectors measure emitted fluorescence.

Question 83: What is the primary stain used to differentiate gram-positive from gram-negative bacteria?

Wright stain
Acid-fast stain
Giemsa stain
Gram stain (Correct answer)

Correct answer: Gram stain

The Gram stain uses crystal violet and safranin to classify bacteria based on cell wall composition.

Question 84: Which of the following blood components must be stored at 20-24°C with continuous, gentle agitation?

Platelets (Correct answer)
Red Blood Cells (RBCs)
Cryoprecipitate
Fresh Frozen Plasma (FFP)

Correct answer: Platelets

Platelets must be stored at room temperature (20-24°C) with continuous gentle agitation to maintain their viability and prevent aggregation. Red Blood Cells are stored at 1-6°C. Fresh Frozen Plasma and Cryoprecipitate are stored in a frozen state, typically at or below -18°C.

Question 85: A technologist receives four tubes of cerebrospinal fluid (CSF) collected via lumbar puncture. To minimize the chance of a false positive culture due to skin flora contamination from the procedure, which tube is typically designated for microbiology?

Any tube can be used interchangeably
Tube 2 (Correct answer)
Tube 4
Tube 1

Correct answer: Tube 2

CSF is typically collected sequentially into 3 or 4 sterile tubes. Tube 1 is most likely to be contaminated with skin bacteria from the puncture site and is used for chemistry. Tube 2 is traditionally sent to microbiology, as the initial flow of fluid has likely cleared most contaminants. Tube 3 and 4 are generally used for hematology cell counts and other special studies.

Question 86: Which hemoglobin electrophoresis pattern is characteristic of sickle cell trait (HbAS)?

HbA only with elevated HbA2
HbS only with no HbA
HbA greater than HbS with normal HbA2 (Correct answer)
HbS greater than HbA with elevated HbF

Correct answer: HbA greater than HbS with normal HbA2

In sickle cell trait, HbA predominates over HbS (typically 55-60% HbA and 35-40% HbS) with normal HbA2 levels.

Question 87: What is the clinical significance of finding oval fat bodies in a urine sediment?

Renal calculi
Acute tubular necrosis
Lower urinary tract infection
Nephrotic syndrome with lipiduria (Correct answer)

Correct answer: Nephrotic syndrome with lipiduria

Oval fat bodies are renal tubular epithelial cells that have absorbed lipids, characteristic of nephrotic syndrome with significant proteinuria.

Question 88: A blood specimen with a hemoglobin of 7.0 g/dL and a mean corpuscular volume (MCV) of 115 fL is most consistent with which type of anemia?

Sickle cell anemia
Iron deficiency anemia
Megaloblastic anemia (Correct answer)
Anemia of chronic disease

Correct answer: Megaloblastic anemia

Megaloblastic anemia is characterized by a markedly elevated MCV (macrocytosis, typically >100 fL) due to impaired DNA synthesis from vitamin B12 or folate deficiency, resulting in abnormally large red blood cells.

Question 89: Which coagulation pathway is assessed by the activated partial thromboplastin time (aPTT)?

Platelet adhesion pathway
Intrinsic and common pathways (Correct answer)
Intrinsic pathway only
Extrinsic and common pathways

Correct answer: Intrinsic and common pathways

The aPTT evaluates factors in the intrinsic pathway (XII, XI, IX, VIII) and the common pathway (X, V, II, fibrinogen).

Question 90: A trauma patient with blood type O negative arrives at the emergency department. The blood bank has a limited supply of O negative red blood cells. Which of the following blood types can be safely transfused to this patient as an alternative if O negative is unavailable?

B negative
No other type is safe (Correct answer)
A negative
O positive

Correct answer: No other type is safe

For an O negative patient, no other blood type is safely compatible for red cell transfusion. Group O patients have anti-A and anti-B antibodies, so they cannot receive A, B, or AB red cells. As they are Rh negative, transfusing Rh positive blood (like O positive) could cause them to develop anti-D antibodies, which can lead to future transfusion complications. In a dire emergency, O positive might be considered for a male or female past childbearing age, but it is not considered a routinely safe alternative.

Question 91: Which autoantibody is most specific for systemic lupus erythematosus (SLE)?

Anti-smooth muscle antibody (ASMA)
Rheumatoid factor (RF)
Antinuclear antibody (ANA)
Anti-double-stranded DNA (anti-dsDNA) (Correct answer)

Correct answer: Anti-double-stranded DNA (anti-dsDNA)

Anti-dsDNA antibodies are highly specific for SLE and their titers often correlate with disease activity, particularly lupus nephritis.

Question 92: Which of the following is a common inhibitor of PCR found in blood specimens?

EDTA
Heparin (Correct answer)
Lithium heparin versus regular heparin (both equally inhibit)
Sodium citrate

Correct answer: Heparin

Heparin is a potent PCR inhibitor because it binds to DNA polymerase and prevents it from functioning; EDTA-anticoagulated blood is preferred for molecular testing.

Question 93: What does an elevated serum AST-to-ALT ratio greater than 2:1 typically suggest?

Hemolytic anemia
Alcoholic liver disease (Correct answer)
Viral hepatitis
Obstructive jaundice

Correct answer: Alcoholic liver disease

An AST-to-ALT ratio greater than 2:1 is a classic pattern associated with alcoholic liver disease due to alcohol-induced mitochondrial damage releasing more AST.

Question 94: Cold agglutinin disease is most commonly caused by antibodies of which specificity?

Anti-I (Correct answer)
Anti-P1
Anti-Le(a)
Anti-M

Correct answer: Anti-I

Anti-I is the specificity of the monoclonal IgM cold agglutinin produced in cold agglutinin disease, reacting optimally at 0–4°C.

Question 95: The Westgard 2-2s rule is triggered when:

Ten consecutive results fall on one side of the mean
Two consecutive controls exceed the mean by 2 SD in the same direction (Correct answer)
One control result exceeds the mean by 3 SD
Two controls differ from each other by more than 4 SD

Correct answer: Two consecutive controls exceed the mean by 2 SD in the same direction

The 2-2s warning rule is triggered when two consecutive QC results exceed ±2 SD on the same side, suggesting systematic error.

Question 96: HLA typing is most critical before which clinical procedure?

Bone marrow biopsy
Solid organ transplantation (Correct answer)
Autologous blood transfusion
Platelet apheresis donation

Correct answer: Solid organ transplantation

HLA matching between donor and recipient is essential in solid organ transplantation to minimize rejection risk.

Question 97: In flow cytometry, what is the function of the forward scatter (FSC) detector?

To detect fluorescent-labeled antibodies
To count the total number of events
To measure internal granularity and complexity
To measure relative cell size (Correct answer)

Correct answer: To measure relative cell size

Forward scatter is proportional to cell size, allowing differentiation of cell populations based on their relative dimensions.

Question 98: According to OSHA's Bloodborne Pathogen Standard, which of the following is the primary engineering control to reduce needlestick injuries?

Double-gloving
Recapping needles with one hand
Using sharps containers (Correct answer)
Wearing face shields

Correct answer: Using sharps containers

Puncture-resistant sharps containers are the primary engineering control mandated by OSHA for safe disposal of needles and sharps.

Question 99: Which crystal found in acidic urine appears as a hexagonal flat plate and is associated with an inherited metabolic disorder?

Calcium oxalate
Amorphous urates
Uric acid
Cystine (Correct answer)

Correct answer: Cystine

Cystine crystals appear as colorless hexagonal plates in acidic urine and indicate cystinuria, an inherited amino acid transport disorder.

Question 100: What corrective action should be taken when a Levy-Jennings chart shows a sudden upward shift in control values starting after a reagent lot change?

Rerun controls using the previous reagent lot to confirm the new lot is the cause (Correct answer)
Report all patient results since they are within reportable range
Continue testing and monitor for further shifts
Perform a new proficiency testing event

Correct answer: Rerun controls using the previous reagent lot to confirm the new lot is the cause

When a shift coincides with a reagent lot change, rerunning controls with the previous lot helps confirm whether the new reagent is causing the problem.

Medical Laboratory Technician (MLT) Exam

The Medical Laboratory Technician (MLT) Exam exam validates essential knowledge and skills required for certification or licensure in this field.

100

Questions

120 min

Time Limit

60%

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