Chemical Pathology MCQs

## Section 1: General Clinical Chemistry **Question 1:** Which of the following is NOT measured in a basic metabolic panel (BMP)? - A) Glucose - B) Creatinine - C) Bilirubin - D) Sodium **Correct Answer:** C) Bilirubin **Explanation:** A BMP typically includes glucose, electrolytes (Na+, K+, Cl-, CO2), BUN, and creatinine. Bilirubin is part of liver function tests, not the BMP. **Question 2:** Which test is the most specific for liver function? - A) ALT - B) AST - C) ALP - D) GGT **Correct Answer:** A) ALT **Explanation:** ALT (Alanine aminotransferase) is more specific for hepatocellular injury as it's primarily found in the liver, while AST is found in multiple organs including heart and muscle. **Question 3:** Which electrolyte is the most abundant cation in extracellular fluid? - A) Sodium - B) Potassium - C) Calcium - D) Magnesium **Correct Answer:** A) Sodium **Explanation:** Sodium (Na+) is the predominant cation in extracellular fluid (normal: 135-145 mEq/L), while potassium is the main intracellular cation. **Question 4:** An increased anion gap metabolic acidosis can be caused by: - A) Diarrhea - B) Lactic acidosis - C) Renal tubular acidosis - D) Hyperaldosteronism **Correct Answer:** B) Lactic acidosis **Explanation:** Lactic acidosis causes increased anion gap metabolic acidosis due to organic acid accumulation. Diarrhea and RTA typically cause normal anion gap acidosis. **Question 5:** Which analyte is most useful in the diagnosis of multiple myeloma? - A) Serum iron - B) Beta-2 microglobulin - C) Serum protein electrophoresis - D) Alkaline phosphatase **Correct Answer:** C) Serum protein electrophoresis **Explanation:** SPEP detects monoclonal proteins (M-proteins) characteristic of multiple myeloma, showing abnormal immunoglobulin bands. ## Section 2: Endocrine Disorders & Hormone Assays **Question 6:** Which of the following is an adrenal hormone? - A) T3 - B) Cortisol - C) Prolactin - D) ADH **Correct Answer:** B) Cortisol **Explanation:** Cortisol is produced by the adrenal cortex. T3 is thyroid hormone, prolactin is pituitary hormone, and ADH is produced by the hypothalamus. **Question 7:** In primary hypothyroidism, TSH levels are typically: - A) High - B) Low - C) Normal - D) Undetectable **Correct Answer:** A) High **Explanation:** Primary hypothyroidism involves thyroid gland failure, so TSH is elevated due to loss of negative feedback from low thyroid hormones. **Question 8:** Which hormone is most useful for diagnosing acromegaly? - A) Cortisol - B) Growth hormone - C) IGF-1 - D) ACTH **Correct Answer:** C) IGF-1 **Explanation:** IGF-1 is more stable than GH and better reflects long-term GH secretion, making it the preferred screening test for acromegaly. **Question 9:** Which test is used to confirm Cushing's syndrome? - A) Serum cortisol at 8 AM - B) Low-dose dexamethasone suppression test - C) Serum ACTH - D) 24-hour urine free cortisol **Correct Answer:** B) Low-dose dexamethasone suppression test **Explanation:** This test differentiates normal individuals (who suppress cortisol) from those with Cushing's syndrome (who fail to suppress). **Question 10:** Which enzyme deficiency is most common in congenital adrenal hyperplasia? - A) 21-hydroxylase - B) 17-hydroxylase - C) 11β-hydroxylase - D) 5α-reductase **Correct Answer:** A) 21-hydroxylase **Explanation:** 21-hydroxylase deficiency accounts for ~95% of CAH cases, leading to cortisol deficiency and androgen excess. ## Section 3: Kidney Function & Electrolytes **Question 11:** The best marker for glomerular filtration rate (GFR) is: - A) Serum creatinine - B) Blood urea nitrogen (BUN) - C) Creatinine clearance - D) Serum cystatin C **Correct Answer:** D) Serum cystatin C **Explanation:** Cystatin C is less affected by muscle mass, age, and diet compared to creatinine, providing a more accurate GFR assessment. **Question 12:** A low fractional excretion of sodium (FENa) suggests: - A) Acute tubular necrosis - B) Prerenal azotemia - C) Hyperkalemia - D) Hypocalcemia **Correct Answer:** B) Prerenal azotemia **Explanation:** FENa <1% indicates intact tubular function with appropriate sodium retention, typical of prerenal causes of AKI. **Question 13:** Which electrolyte abnormality is associated with ECG changes such as peaked T waves? - A) Hypocalcemia - B) Hyperkalemia - C) Hypernatremia - D) Hypomagnesemia **Correct Answer:** B) Hyperkalemia **Explanation:** Hyperkalemia causes characteristic ECG changes: peaked T waves, widened QRS, and can progress to sine waves and cardiac arrest. **Question 14:** Which acid-base disorder is commonly seen in patients with chronic kidney disease? - A) Metabolic acidosis - B) Metabolic alkalosis - C) Respiratory acidosis - D) Respiratory alkalosis **Correct Answer:** A) Metabolic acidosis **Explanation:** CKD causes metabolic acidosis due to decreased acid excretion, reduced ammonia production, a