Clinical Pathology Flashcards

A patient's peripheral smear shows schistocytes, thrombocytopenia, and elevated LDH with normal coagulation studies. Which condition is most consistent?

Answer: Thrombotic thrombocytopenic purpura

TTP causes microangiopathic hemolytic anemia with schistocytes and thrombocytopenia while PT/PTT remain normal.

Which reference method is considered the gold standard for measuring serum osmolality?

Answer: Freezing point depression osmometry

Freezing point depression is the accepted reference method for laboratory osmolality measurement.

A high anion gap metabolic acidosis with elevated osmolal gap most strongly suggests ingestion of which substance?

Answer: Ethylene glycol

Ethylene glycol raises both the anion gap and the osmolal gap due to unmeasured osmoles and acidic metabolites.

Which hemoglobin variant elutes in the same HbA2 window on standard cation-exchange HPLC and can falsely elevate HbA2?

Answer: Hemoglobin E

Hemoglobin E co-elutes with HbA2 on many HPLC systems, causing a spuriously high HbA2 value.

In a mixing study, a prolonged PTT that fails to correct after mixing with normal plasma indicates the presence of a(n):

Answer: Inhibitor

Failure to correct on mixing indicates an inhibitor rather than a simple factor deficiency, which would correct.

Which analyte is most affected by prolonged tourniquet application and fist clenching during venipuncture?

Answer: Potassium

Muscle contraction and stasis release potassium from cells, spuriously elevating serum potassium.

A monoclonal spike in the gamma region on serum protein electrophoresis with Bence Jones proteinuria is most characteristic of:

Answer: Multiple myeloma

A monoclonal M-spike with free light chains in urine (Bence Jones protein) is the hallmark of multiple myeloma.