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CLINICAL CHEMISTRY EXAM QUESTIONS AND CORRECT ANSWERS
LATEST EDITION 2026
Clinical Chemistry —Questions
Chapter 1: Laboratory Basics, Units, and Specimen Handling
1. Which specimen type is preferred for most clinical chemistry tests?
A) Serum
B) Plasma
C) Whole blood
D) Urine
Answer: A
Rationale: Serum is preferred for most chemistry tests because it lacks fibrinogen and other
clotting factors that can interfere with analysis. Plasma is used when rapid turnaround is needed
or when certain analytes are unstable in serum.
2. Which anticoagulant is preferred for plasma glucose testing?
A) EDTA
B) Sodium fluoride/potassium oxalate
C) Heparin
D) Sodium citrate
Answer: B
Rationale: Sodium fluoride inhibits glycolysis, preserving glucose levels. Potassium oxalate is an
anticoagulant. This combination is the standard for glucose testing.
3. Which anticoagulant is preferred for most plasma chemistry tests?
A) EDTA
B) Heparin
C) Sodium citrate
D) Sodium fluoride
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Answer: B
Rationale: Heparin is the preferred anticoagulant for plasma chemistry because it does not
interfere with most analytes and does not chelate ions.
4. Which anticoagulant chelates calcium and is used for coagulation testing?
A) EDTA
B) Heparin
C) Sodium citrate
D) Sodium fluoride
Answer: C
Rationale: Sodium citrate chelates calcium, preventing coagulation. It is the standard
anticoagulant for coagulation testing.
5. What is the recommended order of draw for blood collection?
A) Blood culture, citrate, serum, heparin, EDTA, fluoride
B) EDTA, citrate, serum, heparin, fluoride
C) Serum, EDTA, citrate, heparin, fluoride
D) Heparin, EDTA, citrate, serum, fluoride
Answer: A
Rationale: The CLSI order of draw is: blood culture, citrate (light blue), serum (red/gold),
heparin (green), EDTA (lavender), fluoride (gray). This prevents cross-contamination of additives.
6. What is the purpose of a serum separator tube (SST)?
A) Separates serum from cells during centrifugation
B) Prevents coagulation
C) Preserves glucose
D) Chelates calcium
Answer: A
Rationale: SST contains a gel that separates serum from cells during centrifugation, preventing
analyte exchange between cells and serum.
7. What is the maximum recommended tourniquet application time?
A) 30 seconds
B) 1 minute
C) 2 minutes
D) 5 minutes
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Answer: B
Rationale: Tourniquet application should not exceed 1 minute. Prolonged application causes
hemoconcentration, increasing potassium, lactate, and other analytes.
8. Which analyte is most affected by prolonged tourniquet application?
A) Sodium
B) Potassium
C) Chloride
D) Bicarbonate
Answer: B
Rationale: Prolonged tourniquet application causes hemoconcentration and increased
potassium due to leakage from cells.
9. What is the effect of hemolysis on serum potassium?
A) Falsely decreased
B) Falsely increased
C) No effect
D) Variable
Answer: B
Rationale: Hemolysis releases potassium from red blood cells, falsely increasing serum
potassium.
10. What is the effect of hemolysis on serum lactate dehydrogenase (LD)?
A) Falsely decreased
B) Falsely increased
C) No effect
D) Variable
Answer: B
Rationale: Hemolysis releases LD from red blood cells, falsely increasing serum LD.
11. What is the effect of lipemia on chemistry testing?
A) Interferes with spectrophotometric readings
B) Increases analyte concentration
C) Decreases analyte concentration
D) No effect
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Answer: A
Rationale: Lipemia causes turbidity that interferes with spectrophotometric readings, falsely
elevating or lowering results depending on the method.
12. What is the effect of icterus on chemistry testing?
A) Interferes with spectrophotometric readings
B) Increases analyte concentration
C) Decreases analyte concentration
D) No effect
Answer: A
Rationale: Icterus (bilirubin) absorbs light and interferes with spectrophotometric readings.
13. What is the recommended storage temperature for most serum chemistry analytes?
A) Room temperature
B) 4°C
C) -20°C
D) -80°C
Answer: B
Rationale: Most serum chemistry analytes are stable at 4°C for short-term storage. Long-term
storage requires -20°C or -80°C.
14. Which analyte is unstable at room temperature and requires prompt separation?
A) Sodium
B) Potassium
C) Glucose
D) Chloride
Answer: C
Rationale: Glucose is consumed by cells via glycolysis at room temperature. Prompt separation
or fluoride tubes are required.
15. What is the purpose of a critical value?
A) A result that requires immediate notification of the provider
B) A normal result
C) A slightly abnormal result
D) A result that requires repeat testing
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CLINICAL CHEMISTRY EXAM QUESTIONS AND CORRECT ANSWERS
LATEST EDITION 2026
Clinical Chemistry —Questions
Chapter 1: Laboratory Basics, Units, and Specimen Handling
1. Which specimen type is preferred for most clinical chemistry tests?
A) Serum
B) Plasma
C) Whole blood
D) Urine
Answer: A
Rationale: Serum is preferred for most chemistry tests because it lacks fibrinogen and other
clotting factors that can interfere with analysis. Plasma is used when rapid turnaround is needed
or when certain analytes are unstable in serum.
2. Which anticoagulant is preferred for plasma glucose testing?
A) EDTA
B) Sodium fluoride/potassium oxalate
C) Heparin
D) Sodium citrate
Answer: B
Rationale: Sodium fluoride inhibits glycolysis, preserving glucose levels. Potassium oxalate is an
anticoagulant. This combination is the standard for glucose testing.
3. Which anticoagulant is preferred for most plasma chemistry tests?
A) EDTA
B) Heparin
C) Sodium citrate
D) Sodium fluoride
1|Page
,Page 2 of 59
Answer: B
Rationale: Heparin is the preferred anticoagulant for plasma chemistry because it does not
interfere with most analytes and does not chelate ions.
4. Which anticoagulant chelates calcium and is used for coagulation testing?
A) EDTA
B) Heparin
C) Sodium citrate
D) Sodium fluoride
Answer: C
Rationale: Sodium citrate chelates calcium, preventing coagulation. It is the standard
anticoagulant for coagulation testing.
5. What is the recommended order of draw for blood collection?
A) Blood culture, citrate, serum, heparin, EDTA, fluoride
B) EDTA, citrate, serum, heparin, fluoride
C) Serum, EDTA, citrate, heparin, fluoride
D) Heparin, EDTA, citrate, serum, fluoride
Answer: A
Rationale: The CLSI order of draw is: blood culture, citrate (light blue), serum (red/gold),
heparin (green), EDTA (lavender), fluoride (gray). This prevents cross-contamination of additives.
6. What is the purpose of a serum separator tube (SST)?
A) Separates serum from cells during centrifugation
B) Prevents coagulation
C) Preserves glucose
D) Chelates calcium
Answer: A
Rationale: SST contains a gel that separates serum from cells during centrifugation, preventing
analyte exchange between cells and serum.
7. What is the maximum recommended tourniquet application time?
A) 30 seconds
B) 1 minute
C) 2 minutes
D) 5 minutes
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Answer: B
Rationale: Tourniquet application should not exceed 1 minute. Prolonged application causes
hemoconcentration, increasing potassium, lactate, and other analytes.
8. Which analyte is most affected by prolonged tourniquet application?
A) Sodium
B) Potassium
C) Chloride
D) Bicarbonate
Answer: B
Rationale: Prolonged tourniquet application causes hemoconcentration and increased
potassium due to leakage from cells.
9. What is the effect of hemolysis on serum potassium?
A) Falsely decreased
B) Falsely increased
C) No effect
D) Variable
Answer: B
Rationale: Hemolysis releases potassium from red blood cells, falsely increasing serum
potassium.
10. What is the effect of hemolysis on serum lactate dehydrogenase (LD)?
A) Falsely decreased
B) Falsely increased
C) No effect
D) Variable
Answer: B
Rationale: Hemolysis releases LD from red blood cells, falsely increasing serum LD.
11. What is the effect of lipemia on chemistry testing?
A) Interferes with spectrophotometric readings
B) Increases analyte concentration
C) Decreases analyte concentration
D) No effect
3|Page
, Page 4 of 59
Answer: A
Rationale: Lipemia causes turbidity that interferes with spectrophotometric readings, falsely
elevating or lowering results depending on the method.
12. What is the effect of icterus on chemistry testing?
A) Interferes with spectrophotometric readings
B) Increases analyte concentration
C) Decreases analyte concentration
D) No effect
Answer: A
Rationale: Icterus (bilirubin) absorbs light and interferes with spectrophotometric readings.
13. What is the recommended storage temperature for most serum chemistry analytes?
A) Room temperature
B) 4°C
C) -20°C
D) -80°C
Answer: B
Rationale: Most serum chemistry analytes are stable at 4°C for short-term storage. Long-term
storage requires -20°C or -80°C.
14. Which analyte is unstable at room temperature and requires prompt separation?
A) Sodium
B) Potassium
C) Glucose
D) Chloride
Answer: C
Rationale: Glucose is consumed by cells via glycolysis at room temperature. Prompt separation
or fluoride tubes are required.
15. What is the purpose of a critical value?
A) A result that requires immediate notification of the provider
B) A normal result
C) A slightly abnormal result
D) A result that requires repeat testing
4|Page
