Laboratory Science Clinical Chemistry 2 — Questions and Answers
Question 1: Which electrolyte imbalance is most commonly associated with cardiac arrhythmias?
- Hyponatremia
- Hypochloremia
- Hypokalemia or hyperkalemia (Correct answer)
- Hypocalcemia only
Correct answer: Hypokalemia or hyperkalemia
Both hypokalemia and hyperkalemia alter the cardiac action potential, leading to potentially life-threatening arrhythmias; potassium is the most critical electrolyte for cardiac rhythm.
Question 2: What does an anion gap calculation help identify?
- Type of hemoglobin disorder
- Cause of metabolic acidosis (distinguishing gap from non-gap acidosis) (Correct answer)
- Severity of respiratory alkalosis
- Degree of dehydration
Correct answer: Cause of metabolic acidosis (distinguishing gap from non-gap acidosis)
Anion gap = Na⁺ − (Cl⁻ + HCO₃⁻); an elevated gap suggests accumulation of unmeasured anions (lactate, ketones, toxins), distinguishing high-gap from normal-gap metabolic acidosis.
Question 3: Which pancreatic enzyme is elevated in acute pancreatitis and peaks within 24 hours of onset?
- Lipase only
- Amylase (rises faster but falls sooner) (Correct answer)
- Trypsin
- Elastase
Correct answer: Amylase (rises faster but falls sooner)
Serum amylase rises within 2–12 hours of acute pancreatitis onset and peaks within 24 hours, though lipase is more specific and remains elevated longer.
Question 4: What is the Henderson-Hasselbalch equation used for in clinical chemistry?
- Calculating osmolality
- Relating blood pH to bicarbonate and dissolved CO₂ concentration (Correct answer)
- Determining protein binding of drugs
- Calculating creatinine clearance
Correct answer: Relating blood pH to bicarbonate and dissolved CO₂ concentration
The Henderson-Hasselbalch equation (pH = pKa + log[HCO₃⁻/0.0307×pCO₂]) describes the relationship between pH, bicarbonate, and CO₂, critical for interpreting acid-base disorders.
Question 5: Elevated serum bilirubin causing jaundice can be differentiated into pre-hepatic, hepatic, and post-hepatic types by measuring:
- Total protein and albumin
- Direct (conjugated) vs. indirect (unconjugated) bilirubin fractions (Correct answer)
- ALT and AST ratio
- Bile acid levels only
Correct answer: Direct (conjugated) vs. indirect (unconjugated) bilirubin fractions
Direct (conjugated) hyperbilirubinemia suggests hepatic or post-hepatic obstruction, while indirect (unconjugated) hyperbilirubinemia suggests pre-hepatic hemolysis or Gilbert syndrome.
Question 6: Which lipoprotein fraction is considered 'good cholesterol' due to its cardioprotective role?
- LDL (low-density lipoprotein)
- VLDL (very low-density lipoprotein)
- HDL (high-density lipoprotein) (Correct answer)
- Chylomicrons
Correct answer: HDL (high-density lipoprotein)
HDL transports cholesterol from peripheral tissues back to the liver for excretion (reverse cholesterol transport), and higher HDL levels are associated with reduced cardiovascular risk.
Laboratory Science Clinical Chemistry 2
Which electrolyte imbalance is most commonly associated with cardiac arrhythmias?