ABPath Chemical Pathology 2 — Questions and Answers
Question 1: Which analyte is most affected by prolonged tourniquet application during venipuncture?
- Potassium (Correct answer)
- Sodium
- Chloride
- Glucose
Correct answer: Potassium
Venous stasis and hemoconcentration falsely elevate potassium due to leakage from cells and muscle activity.
Question 2: An elevated anion gap metabolic acidosis with high osmolar gap suggests ingestion of which substance?
- Ethylene glycol (Correct answer)
- Aspirin
- Ammonium chloride
- Acetazolamide
Correct answer: Ethylene glycol
Ethylene glycol raises both the anion gap (from metabolic acids) and the osmolar gap (from the parent alcohol).
Question 3: Which is the most sensitive and specific biomarker for acute myocardial infarction?
- Cardiac troponin I/T (Correct answer)
- CK-MB
- Myoglobin
- LDH
Correct answer: Cardiac troponin I/T
Cardiac troponin has near-absolute myocardial tissue specificity and remains the gold-standard marker.
Question 4: A low TSH with elevated free T4 is most consistent with which condition?
- Primary hyperthyroidism (Correct answer)
- Primary hypothyroidism
- Secondary hypothyroidism
- Euthyroid sick syndrome
Correct answer: Primary hyperthyroidism
Excess thyroid hormone from the gland suppresses pituitary TSH via negative feedback.
Question 5: Which finding best confirms a diagnosis of diabetes mellitus in an asymptomatic patient?
- HbA1c of 6.8% confirmed on repeat testing (Correct answer)
- Random glucose of 150 mg/dL
- Fasting glucose of 115 mg/dL
- Single HbA1c of 6.0%
Correct answer: HbA1c of 6.8% confirmed on repeat testing
An HbA1c ≥6.5% confirmed on a separate occasion meets diagnostic criteria for diabetes.
Question 6: Pseudohyponatremia is classically caused by which of the following?
- Severe hyperlipidemia or hyperproteinemia (Correct answer)
- Adrenal insufficiency
- SIADH
- Diuretic use
Correct answer: Severe hyperlipidemia or hyperproteinemia
High lipids or proteins displace plasma water, causing a spurious low sodium with indirect ion-selective electrodes.
Question 7: Which enzyme elevation is most specific for acute pancreatitis?
- Lipase (Correct answer)
- Amylase
- ALT
- Alkaline phosphatase
Correct answer: Lipase
Lipase is more specific and stays elevated longer than amylase in acute pancreatitis.
ABPath Chemical Pathology 2
Which analyte is most affected by prolonged tourniquet application during venipuncture?