ASCP Board of Certification (BOC) Medical Technologist (MT) / Medical Laboratory Scientist (MLS) — Questions and Answers

Question 1: Which alkaline phosphatase isoenzyme is the most heat-stable when serum is heated at 56°C?

Liver
Bone
Placental (Correct answer)
Intestinal

Correct answer: Placental

Placental ALP resists heat inactivation at 56°C, while bone ALP is the most heat-labile.

Question 2: A urine reagent strip shows a strongly positive blood reaction, but microscopy reveals no RBCs, and the patient's serum is clear with markedly elevated CK. What is the most likely cause?

Hematuria with RBC lysis in dilute urine
Ascorbic acid interference
Hemoglobinuria from intravascular hemolysis
Myoglobinuria from rhabdomyolysis (Correct answer)

Correct answer: Myoglobinuria from rhabdomyolysis

Myoglobin is peroxidase-active and clears rapidly from plasma, so serum stays clear while CK rises after muscle injury.

Question 3: A serum protein electrophoresis shows beta-gamma bridging. This pattern is most suggestive of:

Acute inflammation
Hepatic cirrhosis (Correct answer)
Nephrotic syndrome
Multiple myeloma

Correct answer: Hepatic cirrhosis

Polyclonal IgA rises in cirrhosis and fills in the zone between the beta and gamma bands.

Question 4: Bence Jones proteins in urine are best detected by:

Urine culture
Dipstick protein pad
Sulfosalicylic acid test
Heat precipitation at 60°C then redissolving at 100°C (Correct answer)

Correct answer: Heat precipitation at 60°C then redissolving at 100°C

Bence Jones proteins precipitate at 40–60°C and redissolve when heated to near boiling, distinguishing them from albumin.

Question 5: Which immunoglobulin class crosses the placenta and gives the newborn passive immunity?

IgD
IgM
IgA
IgG (Correct answer)

Correct answer: IgG

IgG is the only immunoglobulin actively carried across the placenta, through the neonatal Fc receptor (FcRn).

Question 6: Elevated serum amylase, normal lipase, and a low urine amylase in an asymptomatic patient most likely indicates:

Acute pancreatitis
Mumps
Renal failure
Macroamylasemia (Correct answer)

Correct answer: Macroamylasemia

Amylase bound to immunoglobulin is too large to be filtered, so serum levels rise and urine levels fall.

Question 7: Which identifier is NOT acceptable when confirming an inpatient's identity before a draw?

Date of birth
Medical record number
Bed or room number (Correct answer)
Full name

Correct answer: Bed or room number

Room or bed numbers can change and are not patient-specific, so they are not valid identifiers.

Question 8: Which organ is primarily responsible for producing albumin?

Liver (Correct answer)
Kidney
Pancreas
Spleen

Correct answer: Liver

The liver is the primary site for the synthesis of most plasma proteins, including albumin. Albumin is a crucial protein responsible for maintaining oncotic pressure and transporting various substances in the blood. Dysfunction of the liver can lead to decreased albumin production, impacting these vital functions and indicating liver disease.

Question 9: According to Beer's law, absorbance is:

Inversely proportional to concentration
Directly proportional to concentration (Correct answer)
Independent of path length
Logarithmically related to concentration

Correct answer: Directly proportional to concentration

A = abc, so absorbance increases linearly with concentration at a fixed path length.

Question 10: In the Davidsohn differential test for infectious mononucleosis, heterophile antibodies are:

Absorbed by both
Absorbed by guinea pig kidney but not beef erythrocytes
Absorbed by neither
Absorbed by beef erythrocytes but not guinea pig kidney (Correct answer)

Correct answer: Absorbed by beef erythrocytes but not guinea pig kidney

IM heterophile antibodies are absorbed by beef RBCs but not by guinea pig kidney, unlike Forssman antibodies.

Question 11: An encapsulated yeast from CSF is urease positive and produces brown colonies on birdseed agar. What is the organism?

Candida albicans
Rhodotorula mucilaginosa
Trichosporon asahii
Cryptococcus neoformans (Correct answer)

Correct answer: Cryptococcus neoformans

C. neoformans is urease positive and has phenoloxidase that forms melanin on birdseed agar.

Question 12: The Kleihauer-Betke test is used to:

Detect fetal-maternal hemorrhage by quantifying fetal cells in maternal blood (Correct answer)
Detect sickle cell trait
Diagnose G6PD deficiency
Type and screen Rh antigens

Correct answer: Detect fetal-maternal hemorrhage by quantifying fetal cells in maternal blood

The Kleihauer-Betke acid elution test differentiates fetal (HbF-containing) from adult red cells in maternal blood to estimate the degree of feto-maternal hemorrhage and guide Rh immunoglobulin dosing.

Question 13: An LD isoenzyme 'flipped pattern' (LD1 greater than LD2) is most characteristic of which condition?

Myocardial infarction (Correct answer)
Skeletal muscle trauma
Pulmonary embolism
Viral hepatitis

Correct answer: Myocardial infarction

Cardiac muscle and red cells are rich in LD1, so myocardial injury raises LD1 above LD2.

Question 14: A gram-negative diplococcus from a urethral discharge is oxidase positive and produces acid from glucose only. What is the likely identification?

Neisseria gonorrhoeae (Correct answer)
Moraxella catarrhalis
Neisseria lactamica
Neisseria meningitidis

Correct answer: Neisseria gonorrhoeae

N. gonorrhoeae oxidizes glucose only, while N. meningitidis uses glucose and maltose.

Question 15: The overnight dexamethasone suppression test is mainly used to screen for:

Pheochromocytoma
Conn syndrome
Cushing syndrome (Correct answer)
Addison disease

Correct answer: Cushing syndrome

Normal people suppress morning cortisol after dexamethasone, but autonomous hypercortisolism does not suppress.

Question 16: What is the minimum interval between standard allogeneic whole blood donations?

112 days
16 weeks
56 days (Correct answer)
28 days

Correct answer: 56 days

Whole blood donors must wait at least 8 weeks (56 days), while double red cell donors wait 112 days.

Question 17: For phenotypic ESBL confirmation, which result is positive?

No zone change with boronic acid
Cloverleaf indentation with ertapenem
Zone increase of ≥5 mm with clavulanate added to ceftazidime or cefotaxime (Correct answer)
Zone decrease of ≥5 mm with clavulanate added

Correct answer: Zone increase of ≥5 mm with clavulanate added to ceftazidime or cefotaxime

CLSI defines ESBL confirmation as a ≥5 mm zone increase when clavulanic acid is added.

Question 18: When should a sharps disposal container be replaced?

Once per week regardless of volume
Only when the lid no longer closes
When it is about three-quarters full (Correct answer)
When it is completely full

Correct answer: When it is about three-quarters full

Replacing at about three-quarters full prevents overfilling and needlestick injuries.

Question 19: What is the preferred substrate for indirect immunofluorescence ANA testing?

Crithidia luciliae
Rat liver sections
Monkey esophagus
HEp-2 cells (Correct answer)

Correct answer: HEp-2 cells

HEp-2 human epithelial cells have large nuclei and dividing cells, so many antigens and patterns can be seen.

Question 20: Which evidence-based approach is most important when applying medical ethics and law principles?

Following personal clinical intuition only
Relying solely on textbook guidelines from any era
Integrating current research with clinical expertise and patient values (Correct answer)
Using the most expensive available treatment

Correct answer: Integrating current research with clinical expertise and patient values

Evidence-based practice in ${subj.toLowerCase()} requires integrating current research findings with clinical expertise and individual patient values.

Question 21: A patient taking high-dose vitamin C supplements may show which reagent strip error?

False-negative glucose and blood (Correct answer)
False-positive nitrite
False-negative specific gravity
False-positive protein

Correct answer: False-negative glucose and blood

Ascorbic acid is a strong reducing agent that interferes with the peroxide-based oxidation reactions for glucose and blood.

Question 22: Which of the following is a Gram-positive cocci?

Neisseria gonorrhoeae
E. coli
Staphylococcus aureus (Correct answer)
Klebsiella pneumoniae

Correct answer: Staphylococcus aureus

Staphylococcus aureus is a classic example of a Gram-positive coccus, meaning it stains purple with the Gram stain and has a spherical shape. It often forms grape-like clusters. In contrast, E. coli and Klebsiella pneumoniae are Gram-negative rods, and Neisseria gonorrhoeae is a Gram-negative coccus, highlighting the importance of Gram staining for bacterial classification.

Question 23: Which crossmatch technique detects most clinically significant alloantibodies that may cause hemolytic transfusion reactions?

Room temperature saline crossmatch
Immediate spin crossmatch only
Antihuman globulin (AHG) crossmatch (Correct answer)
Electronic crossmatch

Correct answer: Antihuman globulin (AHG) crossmatch

The AHG crossmatch (indirect Coombs phase) detects IgG alloantibodies that react at 37°C and are associated with hemolytic reactions.

Question 24: Which analytical principle do ion-selective electrodes use to measure sodium and potassium?

Potentiometry (Correct answer)
Amperometry
Nephelometry
Coulometry

Correct answer: Potentiometry

Ion-selective electrodes are potentiometric. They measure the voltage difference between the indicator electrode and a reference electrode at essentially zero current, and that voltage relates to ion activity.

Question 25: What are the standard minimum conditions for steam sterilization in a gravity autoclave?

160°C dry heat for 2 hours
134°C at 30 psi for 1 minute
121°C at 15 psi for at least 15 minutes (Correct answer)
100°C at 5 psi for 5 minutes

Correct answer: 121°C at 15 psi for at least 15 minutes

Standard steam sterilization uses 121°C at about 15 psi for at least 15 minutes, longer for dense waste loads.

Question 26: Which enzyme is most specific for myocardial infarction?

LDH
AST
Troponin (Correct answer)
CK-MB

Correct answer: Troponin

Cardiac troponins (I and T) are highly specific and sensitive biomarkers for myocardial injury, making them the preferred test for diagnosing myocardial infarction (heart attack). They are released into the bloodstream when heart muscle cells are damaged or die. While CK-MB is also used, troponin levels rise earlier and remain elevated longer, providing a more definitive diagnosis.

Question 27: Which finding in CSF is most consistent with bacterial meningitis?

Increased protein, decreased glucose, neutrophilia (Correct answer)
Decreased protein, increased glucose, lymphocytosis
Normal protein, normal glucose, RBCs
Increased protein, normal glucose, eosinophilia

Correct answer: Increased protein, decreased glucose, neutrophilia

Bacterial meningitis typically causes elevated CSF protein, reduced glucose (bacteria consume it), and a predominance of neutrophils.

Question 28: A minimum inhibitory concentration (MIC) result helps the clinician primarily to:

Select an antimicrobial and dose likely to inhibit the organism (Correct answer)
Identify the organism to species level
Measure the patient's immune response
Determine whether the infection is viral

Correct answer: Select an antimicrobial and dose likely to inhibit the organism

The MIC is the lowest drug concentration that inhibits visible growth and guides antibiotic selection.

Question 29: A urine culture is plated with a 0.001 mL calibrated loop and grows 50 colonies. What is the colony count?

50,000 CFU/mL (Correct answer)
500 CFU/mL
5,000 CFU/mL
500,000 CFU/mL

Correct answer: 50,000 CFU/mL

Multiply colonies by 1,000 for a 0.001 mL loop: 50 × 1,000 = 50,000 CFU/mL.

Question 30: Oligoclonal bands present in CSF but absent in the matched serum on electrophoresis most strongly suggest:

Breakdown of the blood-brain barrier only
Traumatic tap
Bacterial meningitis
Multiple sclerosis (Correct answer)

Correct answer: Multiple sclerosis

CSF-restricted oligoclonal bands indicate intrathecal IgG synthesis, typical of multiple sclerosis.

Question 31: Which serological test is used to detect syphilis?

RPR (Correct answer)
HCV
ANA
CRP

Correct answer: RPR

RPR (Rapid Plasma Reagin) is a non-treponemal serological test commonly used to screen for syphilis. It detects antibodies (reagins) produced by the body in response to tissue damage caused by the syphilis bacterium, Treponema pallidum. While other tests exist, RPR is a widely adopted and cost-effective screening method, often followed by a treponemal test for confirmation.

Question 32: A patient with blood group A has which naturally occurring antibodies?

Anti-A
Anti-B (Correct answer)
No antibodies
Anti-A and Anti-B

Correct answer: Anti-B

A person with blood group A naturally produces anti-B antibodies, while group B individuals have anti-A; group O individuals have both anti-A and anti-B.

Question 33: A 0.5 McFarland standard corresponds to approximately what bacterial concentration?

1.5 × 10^6 CFU/mL
1.5 × 10^8 CFU/mL (Correct answer)
1.5 × 10^9 CFU/mL
1.5 × 10^7 CFU/mL

Correct answer: 1.5 × 10^8 CFU/mL

A 0.5 McFarland turbidity equals about 1.5 × 10^8 CFU/mL.

Question 34: Two consecutive control results exceed +2 SD on the same side of the mean. This violates which Westgard rule, and what error does it indicate?

1-3s; random error
R-4s; random error
2-2s; systematic error (Correct answer)
10x; random error

Correct answer: 2-2s; systematic error

2-2s rejects a run when two consecutive controls exceed 2 SD on the same side, which signals systematic bias.

Question 35: A 24-hour urine collection begins at 7:00 AM. How should the first void at 7:00 AM be handled?

Send it separately as a random urine
Discard it and then collect all urine through 7:00 AM the next day (Correct answer)
Add it to the container as the first sample
Refrigerate it and add it at the end

Correct answer: Discard it and then collect all urine through 7:00 AM the next day

The first void is discarded because it was formed before the timed period began, while the final void at 7:00 AM next day is kept.

Question 36: Which rapid test presumptively identifies Candida albicans after 2-3 hours of incubation in serum at 37°C?

Nitrate assimilation
Ascospore stain
Germ tube test (Correct answer)
Urease test

Correct answer: Germ tube test

C. albicans forms germ tubes without constriction at the point of origin within 3 hours.

Question 37: Which disinfectant is preferred for skin preparation when collecting blood cultures in adults?

Hydrogen peroxide
Benzalkonium chloride
Chlorhexidine gluconate (Correct answer)
70% isopropyl alcohol alone

Correct answer: Chlorhexidine gluconate

Chlorhexidine (often in alcohol) gives superior, longer-lasting skin antisepsis and lowers contamination rates.

Question 38: Which component binds antigen-antibody complexes to initiate the classical complement pathway?

Factor B
C1q (Correct answer)
C3b
Mannose-binding lectin

Correct answer: C1q

C1q binds the Fc regions of IgM or at least two adjacent IgG molecules, which starts the classical pathway.

Question 39: A urine specific gravity of 1.035 most likely indicates:

Renal failure
Concentrated urine (Correct answer)
Diabetes insipidus
Overhydration

Correct answer: Concentrated urine

A specific gravity of 1.035 is above the normal range (1.003–1.030) and indicates highly concentrated urine, often seen in dehydration.

Question 40: Which medium is recommended for culturing Bordetella pertussis from a nasopharyngeal swab?

Thiosulfate citrate bile salts sucrose agar
Buffered charcoal yeast extract agar
Regan-Lowe agar (Correct answer)
Thayer-Martin agar

Correct answer: Regan-Lowe agar

Regan-Lowe (charcoal-horse blood with cephalexin) supports B. pertussis growth.

Question 41: Which ethical principle is most directly applicable to medical ethics and law?

Beneficence — acting in the patient's best interest (Correct answer)
Maximize facility revenue
Follow the most convenient protocol
Prioritize speed over thoroughness

Correct answer: Beneficence — acting in the patient's best interest

Beneficence, the principle of acting in the patient's best interest, is fundamental to ethical practice in medical ethics and law.

Question 42: Which test is performed to detect unexpected alloantibodies in a patient's plasma before transfusion?

Antibody screen (indirect antiglobulin test) (Correct answer)
Forward ABO typing
Direct antiglobulin test
Reverse ABO typing

Correct answer: Antibody screen (indirect antiglobulin test)

The antibody screen (indirect antiglobulin test) tests the patient's serum against reagent red cells expressing known antigens to detect unexpected alloantibodies.

Question 43: A semen sample from an azoospermic patient has a low volume and a negative fructose test. This suggests:

Prostatic infection
Absence or obstruction of the seminal vesicles (Correct answer)
Normal finding after prolonged abstinence
Antisperm antibodies

Correct answer: Absence or obstruction of the seminal vesicles

Fructose is produced by the seminal vesicles, so its absence indicates their absence or ejaculatory duct obstruction.

Question 44: Above what triglyceride level is the Friedewald LDL calculation considered invalid?

150 mg/dL
400 mg/dL (Correct answer)
1000 mg/dL
200 mg/dL

Correct answer: 400 mg/dL

Above 400 mg/dL, TG/5 no longer gives a reliable VLDL estimate, so LDL should be measured directly.

Question 45: For a plasma ammonia level, the specimen should be:

Placed on ice and analyzed promptly (Correct answer)
Collected from a tight, prolonged tourniquet
Stored at room temperature overnight
Allowed to clot at room temperature for 1 hour

Correct answer: Placed on ice and analyzed promptly

Red cell metabolism and deamination in vitro raise ammonia quickly, so chilling and fast testing are essential.

Question 46: Which coagulation factor is NOT present in clinically significant amounts in cryoprecipitate?

Fibrinogen
Factor IX (Correct answer)
von Willebrand factor
Factor XIII

Correct answer: Factor IX

Cryoprecipitate has fibrinogen, FVIII, vWF, FXIII, and fibronectin, but not factor IX.

Question 47: A technologist sells a patient's lab results to a marketing company. Under HIPAA, this knowing violation for commercial gain can result in:

Civil penalties only, never criminal
Criminal penalties including fines up to $250,000 and up to 10 years in prison (Correct answer)
Loss of the hospital's tax-exempt status only
Only a verbal warning

Correct answer: Criminal penalties including fines up to $250,000 and up to 10 years in prison

HIPAA criminal penalties for obtaining or disclosing PHI with intent to sell reach $250,000 and 10 years imprisonment.

Question 48: What is the standard of care requirement for documentation standards in clinical practice?

The most aggressive treatment available
The level of care a reasonably competent practitioner would provide (Correct answer)
The minimum effort needed to avoid a lawsuit
Whatever the practitioner feels is adequate

Correct answer: The level of care a reasonably competent practitioner would provide

The standard of care is defined as what a reasonably competent practitioner with similar training would provide under similar circumstances.

Question 49: A glucose control has a mean of 250 mg/dL and a standard deviation of 5 mg/dL. What is the coefficient of variation?

50%
2% (Correct answer)
5%
0.5%

Correct answer: 2%

CV = (SD / mean) x 100 = (5/250) x 100 = 2%.

Question 50: Nephelometry quantifies immune complexes by measuring:

Light scattered at an angle from the incident beam (Correct answer)
Radioactivity of labeled antigen
Fluorescence emitted after excitation
Light absorbed straight through the sample

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

Nephelometry detects light scattered by antigen-antibody complexes, usually at an angle such as 70-90°.

Question 51: Arterial blood gas: pH 7.50, pCO2 48 mm Hg, HCO3 36 mmol/L. The interpretation is:

Partially compensated metabolic acidosis
Partially compensated metabolic alkalosis (Correct answer)
Uncompensated respiratory alkalosis
Fully compensated respiratory acidosis

Correct answer: Partially compensated metabolic alkalosis

High pH and high HCO3 indicate metabolic alkalosis, and the raised pCO2 is respiratory compensation that hasn't brought pH back to normal.

Question 52: A small gram-negative coccobacillus grows on chocolate agar but only around an X and V factor strip on a nutrient agar plate. What is the organism?

Haemophilus parainfluenzae
Haemophilus influenzae (Correct answer)
Haemophilus ducreyi
Aggregatibacter aphrophilus

Correct answer: Haemophilus influenzae

H. influenzae requires both hemin (X) and NAD (V) factors.

Question 53: A patient's results are HBsAg negative, anti-HBc negative, and anti-HBs positive. This pattern is most consistent with:

Acute HBV infection
Resolved natural HBV infection
Chronic HBV infection
Immunity due to hepatitis B vaccination (Correct answer)

Correct answer: Immunity due to hepatitis B vaccination

The vaccine contains only HBsAg, so a vaccinated person makes anti-HBs without anti-HBc.

Question 54: A unit of red blood cells with 30 days left before its original expiration date is irradiated today. What is its new expiration?

24 hours from irradiation
14 days from irradiation
28 days from irradiation (Correct answer)
Unchanged original expiration

Correct answer: 28 days from irradiation

Irradiated RBCs expire 28 days after irradiation or on the original date, whichever comes first.

Question 55: Under CLIA, what minimum proficiency testing score is generally required for satisfactory performance on most regulated analytes?

70%
75%
90%
80% (Correct answer)

Correct answer: 80%

Most regulated analytes need at least 80%; ABO/Rh and compatibility testing need 100%.

Question 56: When should the trough level be drawn for therapeutic drug monitoring?

30 minutes after an IV dose
2 hours after an oral dose
Midway between doses
Immediately before the next dose (Correct answer)

Correct answer: Immediately before the next dose

The trough is the lowest concentration, which occurs just before the next dose.

Question 57: An oxidase-positive, non-lactose-fermenting gram-negative rod produces a blue-green pigment and a grape-like odor. What is the most likely identification?

Acinetobacter baumannii
Stenotrophomonas maltophilia
Burkholderia cepacia
Pseudomonas aeruginosa (Correct answer)

Correct answer: Pseudomonas aeruginosa

P. aeruginosa produces pyocyanin and has a characteristic fruity grape odor.

Question 58: Calculate the anion gap: Na+ 140 mmol/L, Cl- 100 mmol/L, HCO3- 24 mmol/L.

16 mmol/L (Correct answer)
40 mmol/L
12 mmol/L
20 mmol/L

Correct answer: 16 mmol/L

AG = Na − (Cl + HCO3) = 140 − 124 = 16 mmol/L.

Question 59: Which ABO blood group is considered the 'universal donor' for red blood cell transfusions?

AB
B
A
O (Correct answer)

Correct answer: O

Group O red blood cells lack A and B antigens, making them compatible with recipients of any ABO blood group in emergency situations.

Question 60: An infant's urine gives a positive Clinitest (copper reduction) but a negative glucose oxidase strip. Which condition should be investigated?

Renal glycosuria
Phenylketonuria
Galactosemia (Correct answer)
Diabetes mellitus

Correct answer: Galactosemia

A non-glucose reducing sugar such as galactose reacts with copper reduction but not the glucose-specific oxidase pad.

Question 61: A gram-negative rod from a wound culture is oxidase-positive and gives off a grape-like odor. What is the most likely organism?

Escherichia coli
Klebsiella pneumoniae
Proteus mirabilis
Pseudomonas aeruginosa (Correct answer)

Correct answer: Pseudomonas aeruginosa

P. aeruginosa is an oxidase-positive nonfermenter with a characteristic grape-like odor, whereas Enterobacterales are oxidase-negative.

Question 62: What is the normal reference range for fasting blood glucose in adults?

50–70 mg/dL
70–99 mg/dL (Correct answer)
126–150 mg/dL
100–125 mg/dL

Correct answer: 70–99 mg/dL

The normal reference range for fasting blood glucose in adults is typically 70–99 mg/dL (3.9–5.5 mmol/L). Values outside this range can indicate conditions like hypoglycemia (too low) or hyperglycemia (too high), which may suggest diabetes or prediabetes. This measurement is a key indicator of an individual's glucose metabolism and overall health.

Question 63: A transfusion reaction presenting with fever, chills, and flank pain minutes after starting a transfusion most suggests:

Acute hemolytic transfusion reaction (Correct answer)
Transfusion-associated circulatory overload (TACO)
Febrile non-hemolytic transfusion reaction
Allergic transfusion reaction

Correct answer: Acute hemolytic transfusion reaction

Fever, chills, and flank pain (from renal involvement) occurring rapidly after transfusion onset are classic signs of an acute hemolytic transfusion reaction due to ABO incompatibility.

Question 64: Which electrolyte abnormality increases the risk of digoxin toxicity and should be corrected during treatment?

Hypokalemia (Correct answer)
Hyperkalemia
Hypernatremia
Hypercalcemia only at low levels

Correct answer: Hypokalemia

Low potassium enhances digoxin binding to Na+/K+-ATPase, increasing toxicity.

Question 65: Urine creatinine 100 mg/dL, plasma creatinine 1.0 mg/dL, 24-hour urine volume 1440 mL. What is the creatinine clearance?

144 mL/min
72 mL/min
1440 mL/min
100 mL/min (Correct answer)

Correct answer: 100 mL/min

1440 mL/day is 1 mL/min, so clearance = (100 × 1)/1.0 = 100 mL/min.

Question 66: Which urine color is most associated with myoglobinuria?

Milky white
Colorless
Yellow-green
Red-brown (Correct answer)

Correct answer: Red-brown

Myoglobin released from damaged muscle gives urine a red-brown or cola-colored appearance and tests positive on the dipstick blood pad.

Question 67: Which laboratory test is used to monitor warfarin therapy?

Bleeding time
aPTT
PT/INR (Correct answer)
Platelet count

Correct answer: PT/INR

Warfarin lowers vitamin K-dependent factors, including factor VII, which shows most clearly in the PT/INR.

Question 68: A nucleolar ANA pattern is most often associated with:

Mixed connective tissue disease
Systemic sclerosis (Correct answer)
Rheumatoid arthritis
Drug-induced lupus

Correct answer: Systemic sclerosis

Nucleolar staining (for example, anti-PM-Scl or anti-fibrillarin) is characteristic of systemic sclerosis.

Question 69: When should a specimen be labeled during collection?

At the nurses' station once all draws are finished
At the bedside, in the patient's presence, right after the draw (Correct answer)
In the laboratory when the specimen is received
Before the draw, with pre-printed labels on empty tubes

Correct answer: At the bedside, in the patient's presence, right after the draw

Labeling in the patient's presence right after collection prevents mislabeled and wrong-blood-in-tube errors.

Question 70: Which GHS pictogram indicates acute toxicity that may be fatal or toxic?

Exclamation mark
Health hazard (silhouette)
Skull and crossbones (Correct answer)
Corrosion

Correct answer: Skull and crossbones

The skull and crossbones pictogram marks acute toxicity in the more severe categories.

Question 71: A donor's red cells are negative with anti-D at immediate spin but positive at the antiglobulin phase of weak D testing. How should the unit be labeled?

Rh-negative with a weak D comment
Rh-positive (Correct answer)
Rh-indeterminate, discard unit
Rh-negative

Correct answer: Rh-positive

Weak D donor units are labeled Rh-positive because they could immunize an Rh-negative recipient.

Question 72: Using the Friedewald equation, what is the calculated LDL for total cholesterol 200 mg/dL, HDL 50 mg/dL, and triglycerides 150 mg/dL?

120 mg/dL (Correct answer)
135 mg/dL
90 mg/dL
150 mg/dL

Correct answer: 120 mg/dL

LDL = TC − HDL − TG/5 = 200 − 50 − 30 = 120 mg/dL.

Question 73: When a blood bank technologist discovers a discrepancy between forward and reverse ABO grouping, the FIRST action should be:

Issue the unit with the forward type result
Report the error and discard all samples
Repeat testing with fresh reagents and a new patient sample (Correct answer)
Call the physician and issue O-negative blood

Correct answer: Repeat testing with fresh reagents and a new patient sample

ABO discrepancies must be resolved before issuing blood; repeating the test with fresh reagents and a new sample rules out technical errors as the first step in the investigation.

Question 74: What analyte is measured to evaluate liver function and detect jaundice?

Sodium
Calcium
Creatinine
Bilirubin (Correct answer)

Correct answer: Bilirubin

Bilirubin is a yellow pigment produced during the breakdown of red blood cells, processed by the liver, and excreted in bile. Elevated levels of bilirubin in the blood (hyperbilirubinemia) cause jaundice, a yellowing of the skin and eyes, and typically indicate liver dysfunction or excessive red blood cell destruction. Measuring bilirubin is crucial for evaluating liver health and diagnosing conditions like hepatitis or gallstones.

Question 75: The maximum storage time for packed red blood cells (pRBCs) in CPDA-1 additive solution at 1–6°C is:

21 days
35 days (Correct answer)
42 days
14 days

Correct answer: 35 days

pRBCs stored in CPDA-1 solution have a shelf life of 35 days at 1–6°C; extended additive solutions (AS-1, AS-3, AS-5) extend storage to 42 days.

Question 76: An anaerobic gram-negative rod grows in 20% bile and is resistant to kanamycin, vancomycin, and colistin special-potency disks. What is the likely identification?

Prevotella melaninogenica
Fusobacterium nucleatum
Porphyromonas gingivalis
Bacteroides fragilis group (Correct answer)

Correct answer: Bacteroides fragilis group

The B. fragilis group is bile tolerant and resistant to all three special-potency disks.

Question 77: Which handling requirement is most critical for a serum bilirubin specimen?

Collect in a fluoride tube
Collect on ice
Keep at 37°C
Protect from light (Correct answer)

Correct answer: Protect from light

Light breaks down bilirubin and causes falsely low results.

Question 78: To inactivate complement in a patient serum sample before certain serologic tests, the serum is heated to:

37°C for 60 minutes
100°C for 5 minutes
56°C for 30 minutes (Correct answer)
65°C for 10 minutes

Correct answer: 56°C for 30 minutes

Heating to 56°C for 30 minutes destroys heat-labile complement components (mainly C1 and C2) without denaturing antibody.

Question 79: A patient insists the technologist draw from an arm on the same side as a recent mastectomy. What is the best response?

Refuse to perform the draw at all
Comply because the patient requested it
Explain that the other arm is safer because of lymphedema and specimen-quality risks, and consult the provider if no alternative exists (Correct answer)
Draw from that arm, using a smaller needle

Correct answer: Explain that the other arm is safer because of lymphedema and specimen-quality risks, and consult the provider if no alternative exists

Drawing on the mastectomy side risks complications, so an explanation and escalation are appropriate.

Question 80: Which blood chemistry test evaluates acid-base balance in the body?

Bicarbonate (Correct answer)
Glucose
Urea
Albumin

Correct answer: Bicarbonate

Bicarbonate (HCO3-) is a crucial component of the body's buffer system, playing a significant role in maintaining acid-base balance. It helps neutralize acids and bases, preventing drastic changes in blood pH, which is vital for proper cellular function. Measuring bicarbonate levels, often as part of an electrolyte panel, is essential for evaluating metabolic acidosis or alkalosis.

Question 81: A pear-shaped flagellate with two nuclei and a sucking disk shows 'falling leaf' motility in a stool wet mount. What is the parasite?

Dientamoeba fragilis
Trichomonas vaginalis
Chilomastix mesnili
Giardia duodenalis (Correct answer)

Correct answer: Giardia duodenalis

Giardia trophozoites are pear-shaped and binucleate, with a ventral sucking disk and falling-leaf motility.

Question 82: How does acute alkalosis affect serum ionized calcium?

Ionized calcium decreases (Correct answer)
Ionized calcium increases
No effect
Total calcium decreases

Correct answer: Ionized calcium decreases

In alkalosis albumin releases H+ and binds more Ca2+, which lowers the free ionized fraction.

Question 83: In Kirby-Bauer disk diffusion testing, what is the required depth of Mueller-Hinton agar?

6 mm
2 mm
3 mm
4 mm (Correct answer)

Correct answer: 4 mm

CLSI specifies 4 mm agar depth, since thicker agar gives falsely small zones and thinner agar falsely large zones.

Question 84: The Rh blood group antigen most commonly responsible for hemolytic disease of the fetus and newborn (HDFN) is:

Rh(D) (Correct answer)
Rh(e)
Rh(E)
Rh(c)

Correct answer: Rh(D)

The D antigen is the most immunogenic Rh antigen; Rh(D)-negative mothers who form anti-D antibodies pose the greatest risk for severe HDFN.

Question 85: A catalase-positive, coagulase-negative staphylococcus from a young woman's urine is resistant to novobiocin. What is the most likely identification?

Staphylococcus saprophyticus (Correct answer)
Staphylococcus lugdunensis
Staphylococcus epidermidis
Staphylococcus aureus

Correct answer: Staphylococcus saprophyticus

S. saprophyticus is the novobiocin-resistant CoNS associated with UTIs in young women.

Question 86: An anaerobic, large boxcar-shaped gram-positive rod shows a double zone of beta-hemolysis on blood agar. What is the most likely organism?

Bacillus anthracis
Clostridioides difficile
Clostridium perfringens (Correct answer)
Clostridium septicum

Correct answer: Clostridium perfringens

C. perfringens shows double-zone hemolysis from theta and alpha toxins.

Question 87: Increased conjugated bilirubin, positive urine bilirubin, and decreased urine urobilinogen most strongly suggest:

Gilbert syndrome
Hemolytic anemia
Biliary obstruction (Correct answer)
Neonatal physiologic jaundice

Correct answer: Biliary obstruction

Blockage stops bilirubin reaching the gut, so urobilinogen falls while water-soluble conjugated bilirubin spills into urine.

Question 88: Fresh frozen plasma (FFP) is indicated for:

Iron deficiency anemia
Hypogammaglobulinemia
Replacement of coagulation factors in a bleeding patient with multiple factor deficiencies (Correct answer)
Thrombocytopenia

Correct answer: Replacement of coagulation factors in a bleeding patient with multiple factor deficiencies

FFP contains all coagulation factors and is indicated for bleeding patients with documented factor deficiencies, liver disease-related coagulopathy, or massive transfusion.

Question 89: Which biosafety level is required for handling Mycobacterium tuberculosis?

BSL-3 (Correct answer)
BSL-1
BSL-2
BSL-4

Correct answer: BSL-3

Mycobacterium tuberculosis, the causative agent of tuberculosis, requires Biosafety Level 3 (BSL-3) containment due to its potential for aerosol transmission and the severity of the disease it causes. BSL-3 facilities include specialized engineering controls, such as negative airflow and HEPA filtration, and strict work practices to protect laboratory personnel from exposure to this highly infectious pathogen.

Question 90: A patient on high-dose IV penicillin has a positive IgG DAT. The eluate reacts only with penicillin-coated red cells. Which mechanism explains this?

Immune complex formation
True autoantibody production
Drug adsorption (hapten) (Correct answer)
Nonimmunologic protein adsorption

Correct answer: Drug adsorption (hapten)

Penicillin binds firmly to the RBC membrane, and the antibody against the drug reacts only with drug-coated cells.

Question 91: Which analyte is most falsely elevated by in vitro hemolysis?

Chloride
Glucose
Sodium
Potassium (Correct answer)

Correct answer: Potassium

Red cells contain about 20 times more potassium than plasma, so lysis releases it into the sample.

Question 92: Cryoprecipitate is the product of choice for which deficiency?

Protein C deficiency
Factor VII deficiency
Factor IX deficiency (hemophilia B)
Fibrinogen deficiency or von Willebrand disease (Correct answer)

Correct answer: Fibrinogen deficiency or von Willebrand disease

Cryoprecipitate is rich in fibrinogen, Factor VIII, von Willebrand factor, and Factor XIII, making it the preferred product for fibrinogen deficiency and vWD.

Question 93: A severely lipemic sample shows low sodium by indirect ISE but normal sodium by direct ISE. This is best explained by:

Hemolysis interference
SIADH
Pseudohyponatremia from the electrolyte exclusion effect (Correct answer)
True dilutional hyponatremia

Correct answer: Pseudohyponatremia from the electrolyte exclusion effect

Lipid takes up plasma volume, and diluting the sample for indirect ISE underestimates sodium in plasma water.

Question 94: Which antibody is most often linked to delayed hemolytic transfusion reactions because its titer often falls below detectable levels?

Anti-Lea
Anti-K
Anti-E
Anti-Jka (Correct answer)

Correct answer: Anti-Jka

Kidd antibodies are known for disappearing from detection and then returning quickly in an anamnestic response after re-exposure.

Question 95: Approximately how many half-lives are needed for a drug on a fixed dosing schedule to reach steady state?

2 to 3
5 to 7 (Correct answer)
10 to 12
1 to 2

Correct answer: 5 to 7

A drug reaches about 97% of steady state after roughly 5 half-lives.

Question 96: The ammoniacal (fishy) odor of urine is most often caused by:

Maple syrup urine disease
Bacterial decomposition of urea (Correct answer)
Diabetic ketoacidosis
Phenylketonuria

Correct answer: Bacterial decomposition of urea

Urease-producing bacteria decompose urea to ammonia, producing the characteristic ammoniacal odor in infected or standing urine samples.

Question 97: Oval fat bodies showing Maltese cross formations under polarized light are characteristic of which disorder?

Acute tubular necrosis from crush injury
Acute pyelonephritis
Nephrotic syndrome (Correct answer)
Cystitis

Correct answer: Nephrotic syndrome

Lipiduria with cholesterol-containing oval fat bodies is a hallmark of nephrotic syndrome.

Question 98: Which test has the highest specificity for rheumatoid arthritis?

Rheumatoid factor (IgM)
Anti-cyclic citrullinated peptide (anti-CCP) (Correct answer)
Erythrocyte sedimentation rate
C-reactive protein

Correct answer: Anti-cyclic citrullinated peptide (anti-CCP)

Anti-CCP is about 95% specific for RA and can appear before clinical symptoms.

Question 99: When differentiating a traumatic tap from true subarachnoid hemorrhage, which finding supports subarachnoid hemorrhage?

Clear supernatant after centrifugation
Uniform RBC count across all tubes (Correct answer)
Clot formation in the collection tube
Decreasing RBC count in successive tubes

Correct answer: Uniform RBC count across all tubes

In subarachnoid hemorrhage, blood is uniformly distributed throughout all CSF collection tubes, while a traumatic tap shows decreasing RBCs in successive tubes.

Question 100: Which method is used for bacterial identification through DNA amplification?

PCR (Correct answer)
ELISA
Agglutination
Western blot

Correct answer: PCR

PCR (Polymerase Chain Reaction) is a molecular biology technique used to amplify specific DNA sequences, making it highly effective for bacterial identification. By targeting unique genetic markers, PCR can rapidly detect and identify bacteria, even when present in very small numbers, without the need for traditional culture methods. This method is crucial for fast and accurate diagnosis in clinical and research settings.

ASCP Board of Certification (BOC) Medical Technologist (MT) / Medical Laboratory Scientist (MLS)

This certification validates the competency of medical laboratory professionals to perform a full range of laboratory tests, analyze results, and ensure accuracy in various clinical settings.

100

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150 min

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