ASCP Clinical Chemistry 3

Question 1

Phenylketonuria (PKU) is detected by measuring elevated levels of which metabolite?

Accepted Answer

Phenylalanine

Answer

PKU results from phenylalanine hydroxylase deficiency, causing phenylalanine accumulation in blood and urine.

Question 2

Which tumor marker is most useful for monitoring treatment response in prostate cancer?

Accepted Answer

PSA

Answer

Prostate-specific antigen (PSA) is produced by prostate epithelium and is the primary biomarker for monitoring prostate cancer.

Question 3

The reference method for cholesterol measurement uses which technique?

Accepted Answer

Abell-Kendall method with Liebermann-Burchard reagent

Answer

The Abell-Kendall method is the CDC reference method for total cholesterol, used to calibrate all clinical enzymatic assays.

Question 4

Which enzyme deficiency causes phenylketonuria?

Accepted Answer

Phenylalanine hydroxylase

Answer

Phenylalanine hydroxylase converts phenylalanine to tyrosine; its deficiency causes toxic phenylalanine accumulation.

Question 5

A serum sodium of 118 mEq/L is classified as:

Accepted Answer

Severe hyponatremia

Answer

Severe hyponatremia is defined as serum sodium below 120–125 mEq/L and requires urgent treatment to prevent cerebral edema.

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