ASCP Medical Laboratory Scientist
(MLS(ASCP)) Certification Examination
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which anticoagulant is commonly used for complete blood count (CBC)
testing?
A. Sodium citrate
B. Heparin
C. EDTA
D. Sodium fluoride
Answer: C. EDTA
Rationale: EDTA preserves cellular morphology by chelating calcium, making it the
preferred anticoagulant for hematology testing.
2. Which specimen is preferred for most routine clinical chemistry tests?
A. Whole blood with EDTA
B. Citrated plasma
C. Serum
D. Urine
Answer: C. Serum
Rationale: Serum is commonly used because it lacks clotting factors that may
interfere with many chemistry assays.
,3. Which organ is the primary site of albumin synthesis?
A. Kidney
B. Spleen
C. Liver
D. Pancreas
Answer: C. Liver
Rationale: Hepatocytes synthesize albumin, the major protein responsible for
maintaining plasma oncotic pressure.
4. Which analyte is the most specific indicator of renal filtration function?
A. ALT
B. Bilirubin
C. Creatinine
D. Amylase
Answer: C. Creatinine
Rationale: Serum creatinine reflects glomerular filtration rate more specifically
than many other routine analytes.
5. Which enzyme is most commonly associated with liver cell injury?
A. CK
B. LDH
C. ALT
D. Lipase
Answer: C. ALT
Rationale: Alanine aminotransferase (ALT) is primarily found in hepatocytes and
increases with liver cell injury.
,6. Which enzyme is most specific for acute pancreatitis?
A. AST
B. ALT
C. Lipase
D. ALP
Answer: C. Lipase
Rationale: Lipase remains elevated longer than amylase and is more specific for
pancreatic injury.
7. Hemoglobin A1c reflects average blood glucose over approximately:
A. 24 hours
B. 1 week
C. 2–3 months
D. 1 year
Answer: C. 2–3 months
Rationale: HbA1c reflects glucose exposure over the lifespan of red blood cells,
approximately 120 days.
8. Which electrolyte is the major extracellular cation?
A. Potassium
B. Calcium
C. Magnesium
D. Sodium
Answer: D. Sodium
Rationale: Sodium is the predominant extracellular cation and plays a major role
in fluid balance.
9. Which electrolyte is the major intracellular cation?
, A. Sodium
B. Chloride
C. Potassium
D. Calcium
Answer: C. Potassium
Rationale: Potassium is the principal intracellular cation involved in nerve and
muscle function.
10. Which hormone primarily lowers blood glucose?
A. Glucagon
B. Cortisol
C. Epinephrine
D. Insulin
Answer: D. Insulin
Rationale: Insulin promotes cellular glucose uptake and lowers blood glucose
concentration.
11. Which quality control practice detects systematic analytical error?
A. Running one patient sample
B. Reviewing quality control trends over time
C. Using expired reagents
D. Ignoring calibration results
Answer: B. Reviewing quality control trends over time
Rationale: Quality control trend analysis helps identify systematic shifts and trends
before patient results are affected.
12. Which laboratory document describes step-by-step testing procedures?
(MLS(ASCP)) Certification Examination
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which anticoagulant is commonly used for complete blood count (CBC)
testing?
A. Sodium citrate
B. Heparin
C. EDTA
D. Sodium fluoride
Answer: C. EDTA
Rationale: EDTA preserves cellular morphology by chelating calcium, making it the
preferred anticoagulant for hematology testing.
2. Which specimen is preferred for most routine clinical chemistry tests?
A. Whole blood with EDTA
B. Citrated plasma
C. Serum
D. Urine
Answer: C. Serum
Rationale: Serum is commonly used because it lacks clotting factors that may
interfere with many chemistry assays.
,3. Which organ is the primary site of albumin synthesis?
A. Kidney
B. Spleen
C. Liver
D. Pancreas
Answer: C. Liver
Rationale: Hepatocytes synthesize albumin, the major protein responsible for
maintaining plasma oncotic pressure.
4. Which analyte is the most specific indicator of renal filtration function?
A. ALT
B. Bilirubin
C. Creatinine
D. Amylase
Answer: C. Creatinine
Rationale: Serum creatinine reflects glomerular filtration rate more specifically
than many other routine analytes.
5. Which enzyme is most commonly associated with liver cell injury?
A. CK
B. LDH
C. ALT
D. Lipase
Answer: C. ALT
Rationale: Alanine aminotransferase (ALT) is primarily found in hepatocytes and
increases with liver cell injury.
,6. Which enzyme is most specific for acute pancreatitis?
A. AST
B. ALT
C. Lipase
D. ALP
Answer: C. Lipase
Rationale: Lipase remains elevated longer than amylase and is more specific for
pancreatic injury.
7. Hemoglobin A1c reflects average blood glucose over approximately:
A. 24 hours
B. 1 week
C. 2–3 months
D. 1 year
Answer: C. 2–3 months
Rationale: HbA1c reflects glucose exposure over the lifespan of red blood cells,
approximately 120 days.
8. Which electrolyte is the major extracellular cation?
A. Potassium
B. Calcium
C. Magnesium
D. Sodium
Answer: D. Sodium
Rationale: Sodium is the predominant extracellular cation and plays a major role
in fluid balance.
9. Which electrolyte is the major intracellular cation?
, A. Sodium
B. Chloride
C. Potassium
D. Calcium
Answer: C. Potassium
Rationale: Potassium is the principal intracellular cation involved in nerve and
muscle function.
10. Which hormone primarily lowers blood glucose?
A. Glucagon
B. Cortisol
C. Epinephrine
D. Insulin
Answer: D. Insulin
Rationale: Insulin promotes cellular glucose uptake and lowers blood glucose
concentration.
11. Which quality control practice detects systematic analytical error?
A. Running one patient sample
B. Reviewing quality control trends over time
C. Using expired reagents
D. Ignoring calibration results
Answer: B. Reviewing quality control trends over time
Rationale: Quality control trend analysis helps identify systematic shifts and trends
before patient results are affected.
12. Which laboratory document describes step-by-step testing procedures?
