Chemical Pathology MCQs — MCQ Bank OmpathStudy

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, and bicarbonate loss. Question 15: Which of the following conditions leads to an increased BUN-to-creatinine ratio? A) Liver failure B) SIADH C) Prerenal azotemia D) Rhabdomyolysis Correct Answer: C) Prerenal azotemia Explanation: Prerenal azotemia increases BUN more than creatinine due to enhanced urea reabsorption, raising the BUN:Cr ratio 20:1. Section 4: Liver Function & Lipid Metab