CLS Clinical Chemistry

Question 1

Which specimen is preferred for most clinical chemistry tests to avoid interference from cellular components?

Accepted Answer

Serum or plasma separated from cells

Answer

Whole blood collected in EDTA

Answer

Urine collected over 24 hours

Answer

Cerebrospinal fluid collected by lumbar puncture

Question 2

A patient's serum glucose is measured at 350 mg/dL. Which method is considered the reference method for glucose measurement in clinical laboratories?

Accepted Answer

Hexokinase method

Answer

Glucose oxidase-peroxidase method

Answer

Orthotoluidine method

Answer

Folin-Wu reduction method

Question 3

Which enzyme is most cardiac-specific and is considered the gold standard biomarker for myocardial infarction diagnosis?

Accepted Answer

Cardiac troponin I or T

Answer

Creatine kinase-MB (CK-MB)

Answer

Lactate dehydrogenase (LDH)

Answer

Aspartate aminotransferase (AST)

Question 4

The normal anion gap range is approximately 8-12 mEq/L. Which formula correctly calculates the anion gap?

Accepted Answer

Na+ - (Cl- + HCO3-)

Answer

Na+ + K+ - (Cl- + HCO3-)

Answer

Na+ - Cl-

Answer

(Na+ + K+) - Cl-

Question 5

Which lipid fraction is inversely associated with cardiovascular disease risk and is often called 'good cholesterol'?

Accepted Answer

HDL cholesterol

Answer

LDL cholesterol

Answer

VLDL cholesterol

Answer

Chylomicrons

Question 6

A serum creatinine of 2.5 mg/dL in an adult patient most likely indicates which condition?

Accepted Answer

Impaired renal function

Answer

Normal renal function

Answer

Hepatic failure

Answer

Hemolytic anemia

Question 7

Which of the following is the most common cause of pseudohyperkalemia in a blood specimen?

Accepted Answer

Hemolysis of red blood cells in the specimen

Answer

Prolonged storage at room temperature

Answer

Use of a lithium heparin tube

Answer

Refrigeration of the specimen before centrifugation