ASCP Clinical Chemistry 2

Question 1

Which method is the reference standard for measuring serum creatinine?

Accepted Answer

Enzymatic method with isotope dilution mass spectrometry (IDMS)

Answer

IDMS-traceable enzymatic creatinine methods are the current reference standards, eliminating pseudochromogen interference seen with Jaffe.

Question 2

A patient has pH 7.28, PCO2 55 mmHg, and HCO3 24 mEq/L. This is consistent with:

Accepted Answer

Respiratory acidosis

Answer

Elevated PCO2 with low pH and normal bicarbonate indicates primary respiratory acidosis from CO2 retention.

Question 3

Which analyte is measured by the Berthelot reaction in clinical chemistry?

Accepted Answer

Ammonia/urea nitrogen (BUN)

Answer

The Berthelot reaction converts ammonia (from urease-hydrolyzed urea) to a colored indophenol compound for BUN measurement.

Question 4

Which fraction of bilirubin is elevated in hepatocellular disease and obstructive jaundice?

Accepted Answer

Both conjugated and unconjugated

Answer

Hepatocellular and obstructive jaundice both elevate conjugated bilirubin, and impaired uptake also elevates unconjugated bilirubin.

Question 5

The Friedewald equation calculates LDL cholesterol using which formula?

Accepted Answer

LDL = Total cholesterol − HDL − (TG/5)

Answer

The Friedewald equation estimates LDL as: Total cholesterol − HDL − (triglycerides/5), valid only when TG < 400 mg/dL.

ASCP Practice Test