ABPath Clinical Pathology 2 — Questions and Answers
Question 1: A patient's peripheral smear shows schistocytes, thrombocytopenia, and elevated LDH with normal coagulation studies. Which condition is most consistent?
- Thrombotic thrombocytopenic purpura (Correct answer)
- Disseminated intravascular coagulation
- Immune thrombocytopenic purpura
- Vitamin K deficiency
Correct answer: Thrombotic thrombocytopenic purpura
TTP causes microangiopathic hemolytic anemia with schistocytes and thrombocytopenia while PT/PTT remain normal.
Question 2: Which reference method is considered the gold standard for measuring serum osmolality?
- Freezing point depression osmometry (Correct answer)
- Refractometry
- Flame photometry
- Ion-selective electrode
Correct answer: Freezing point depression osmometry
Freezing point depression is the accepted reference method for laboratory osmolality measurement.
Question 3: A high anion gap metabolic acidosis with elevated osmolal gap most strongly suggests ingestion of which substance?
- Ethylene glycol (Correct answer)
- Aspirin
- Metformin
- Isoniazid
Correct answer: Ethylene glycol
Ethylene glycol raises both the anion gap and the osmolal gap due to unmeasured osmoles and acidic metabolites.
Question 4: Which hemoglobin variant elutes in the same HbA2 window on standard cation-exchange HPLC and can falsely elevate HbA2?
- Hemoglobin E (Correct answer)
- Hemoglobin S
- Hemoglobin C
- Hemoglobin F
Correct answer: Hemoglobin E
Hemoglobin E co-elutes with HbA2 on many HPLC systems, causing a spuriously high HbA2 value.
Question 5: In a mixing study, a prolonged PTT that fails to correct after mixing with normal plasma indicates the presence of a(n):
- Inhibitor (Correct answer)
- Factor deficiency
- Vitamin K deficiency
- Heparin contamination only
Correct answer: Inhibitor
Failure to correct on mixing indicates an inhibitor rather than a simple factor deficiency, which would correct.
Question 6: Which analyte is most affected by prolonged tourniquet application and fist clenching during venipuncture?
- Potassium (Correct answer)
- Sodium
- Chloride
- Glucose
Correct answer: Potassium
Muscle contraction and stasis release potassium from cells, spuriously elevating serum potassium.
Question 7: A monoclonal spike in the gamma region on serum protein electrophoresis with Bence Jones proteinuria is most characteristic of:
- Multiple myeloma (Correct answer)
- Chronic inflammation
- Nephrotic syndrome
- Alpha-1 antitrypsin deficiency
Correct answer: Multiple myeloma
A monoclonal M-spike with free light chains in urine (Bence Jones protein) is the hallmark of multiple myeloma.
ABPath Clinical Pathology 2
A patient's peripheral smear shows schistocytes, thrombocytopenia, and elevated LDH with normal coagulation studies.
Which condition is most consistent?