Prepare for your exams with our Chemical Pathology MCQs on endocrine & metabolic pathology. Essential practice for Year 3 medical students. Start learning now!
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 20:1. Section 4: Liver Function & Lipid Metabolism Question 16: Which liver enzyme is most specific for hepatocellular injury? - A) ALP - B) AST - C) ALT - D) GGT Correct Answer: C) ALT Explanation: ALT is predominantly found in hepatocytes, making it more specific for liver injury than AST, which is also found in cardiac and skeletal muscle. Question 17: Which of the following is the best marker of cholestasis? - A) ALT - B) ALP - C) Bilirubin - D) Ammonia Correct Answer: B) ALP Explanation: Alkaline phosphatase is elevated in cholestatic conditions due to increased synthesis and release from bile duct epithelium. Question 18: Which lipoprotein is primarily responsible for transporting cholesterol to tissues? - A) HDL - B) LDL - C) VLDL - D) Chylomicrons Correct Answer: B) LDL Explanation: LDL carries cholesterol from liver to peripheral tissues and is the major atherogenic lipoprotein. Question 19: Familial hypercholesterolemia is caused by a defect in which receptor? - A) LDL receptor - B) VLDL receptor - C) Apolipoprotein A-I - D) CETP Correct Answer: A) LDL receptor Explanation: FH is caused by mutations in the LDL receptor gene, leading to impaired cholesterol uptake and very high LDL levels. Question 20: A fasting glucose level of 8.0 mmol/L (144 mg/dL) suggests: - A) Normal glucose metabolism - B) Prediabetes - C) Diabetes mellitus - D) Hypoglycemia Correct Answer: C) Diabetes mellitus Explanation: Fasting glucose ≥7.0 mmol/L (126 mg/dL) indicates diabetes mellitus. 144 mg/dL clearly meets this criterion. Section 5: Tumor Markers & Cancer Screening Question 21: Which tumor marker is most commonly used for ovarian cancer screening? - A) CA 15-3 - B) CA 125 - C) PSA - D) CEA Correct Answer: B) CA 125 Explanation: CA 125 is the most widely used tumor marker for ovarian cancer, though it's not specific and can be elevated in benign conditions. Question 22: A patient with suspected pancreatic cancer is likely to have elevated levels of: - A) AFP - B) CA 19-9 - C) CEA - D) Beta-2 microglobulin Correct Answer: B) CA 19-9 Explanation: CA 19-9 is the most useful tumor marker for pancreatic adenocarcinoma, though it's also elevated in biliary obstruction. Question 23: Which tumor marker is most specific for hepatocellular carcinoma? - A) CA 19-9 - B) AFP - C) PSA - D) CA 15-3 Correct Answer: B) AFP Explanation: Alpha-fetoprotein (AFP) is the most specific tumor marker for hepatocellular carcinoma, though it can also be elevated in other liver diseases. Question 24: A patient with an enlarged prostate and elevated PSA should undergo: - A) Serum testosterone - B) Prostate biopsy - C) Bone scan - D) CT scan Correct Answer: B) Prostate biopsy Explanation: Elevated PSA with enlarged prostate requires tissue diagnosis via biopsy to rule out prostate cancer. Question 25: The presence of high levels of CEA is most suggestive of: - A) Breast cancer - B) Colorectal cancer - C) Prostate cancer - D) Ovarian cancer Correct Answer: B) Colorectal cancer Explanation: CEA (carcinoembryonic antigen) is most commonly associated with colorectal cancer, though it's not specific. Section 6: Acid-Base Disorders & Blood Gases Question 26: Which of the following is a primary metabolic alkalosis? - A) COPD - B) Vomiting - C) Diabetic ketoacidosis - D) Renal failure Correct Answer: B) Vomiting Explanation: Vomiting causes loss of gastric acid (HCl), leading to metabolic alkalosis. COPD causes respiratory acidosis. Question 27: A patient with a pH of 7.25, PaCO₂ of 60 mmHg, and HCO₃⁻ of 24 mEq/L has: - A) Metabolic acidosis - B) Respiratory acidosis - C) Metabolic alkalosis - D) Respiratory alkalosis Correct Answer: B) Respiratory acidosis Explanation: pH 45 mmHg) indicates respiratory acidosis. Normal bicarbonate suggests acute condition. Question 28: Which of the following causes a normal anion gap metabolic acidosis? - A) Lactic acidosis - B) Methanol toxicity - C) Renal tubular acidosis - D) Diabetic ketoacidosis Correct Answer: C) Renal tubular acidosis Explanation: RTA causes normal anion gap acidosis due to impaired re