🩺 USMLE High-Yield Questions

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1. A 60-year-old man presents with crushing chest pain. Most sensitive marker?

A. CK-MB
B. Troponin I
C. Myoglobin
D. LDH

Explanation: Troponin I (and Troponin T) are the most sensitive and specific cardiac markers for myocardial infarction. They rise within 3-4 hours and remain elevated for 7-10 days. CK-MB is less specific (also elevated in skeletal muscle injury), myoglobin rises earliest but is non-specific, and LDH is outdated.

2. Child with edema + massive proteinuria?

A. Minimal Change Disease
B. IgA Nephropathy
C. Post-strep GN
D. Membranous nephropathy

Explanation: Minimal Change Disease is the most common cause of nephrotic syndrome in children. It presents with generalized edema and massive proteinuria (>3.5g/day). It responds dramatically to steroids. Light microscopy is normal, but electron microscopy shows foot process effacement.

3. First-line drug for Type 2 Diabetes?

A. Insulin
B. Metformin
C. Sulfonylureas
D. GLP-1 agonists

Explanation: Metformin is the first-line pharmacologic treatment for Type 2 Diabetes Mellitus (unless contraindicated, e.g., severe renal impairment). It decreases hepatic glucose production, increases insulin sensitivity, and has cardiovascular benefits with low risk of hypoglycemia.

4. Burn patient + grape-like odor pneumonia?

A. Staph aureus
B. Strep pneumoniae
C. Pseudomonas
D. Klebsiella

Explanation: Pseudomonas aeruginosa is a common cause of pneumonia in burn patients. It produces a characteristic sweet, grape-like odor due to 2-aminoacetophenone. It is also associated with green-blue pigment (pyocyanin) and is highly resistant to many antibiotics.

5. Antidote for acetaminophen overdose?

A. Atropine
B. Naloxone
C. N-acetylcysteine
D. Vitamin K

Explanation: N-acetylcysteine (NAC) is the antidote for acetaminophen (paracetamol) overdose. It replenishes glutathione stores and detoxifies the toxic metabolite NAPQI, preventing hepatic necrosis. It is most effective when given within 8 hours of ingestion.