Cardiovascular Drugs USMLE Step 1 Practice Question
A 62-year-old man with a 10-year history of hypertension and type 2 diabetes mellitus presents to clinic for routine follow-up. He reports dyspnea on exertion over the past 2 weeks and notices bilateral ankle edema. Current medications include lisinopril 10 mg daily for 3 years with well-controlled blood pressure (138/82 mmHg), metformin, and atorvastatin. Vital signs: HR 88/min, RR 18/min, BP 138/82 mmHg, SpO2 98% on room air. Physical examination reveals 2+ bilateral ankle edema and bibasilar crackles. Laboratory studies show: Serum creatinine: 1.8 mg/dL (baseline 1.0 mg/dL 6 months ago)
Blood urea nitrogen: 32 mg/dL
Serum potassium: 5.8 mEq/L (normal 3.5-5.0)
Serum sodium: 138 mEq/L
Urine sodium: 45 mEq/day (normal 50-200) Which of the following best explains the development of hyperkalemia and acute kidney injury in this patient?
Answer choices
- ALisinopril blocks angiotensin II formation, leading to decreased glomerular filtration pressure and reduced creatinine clearance, while simultaneously inhibiting aldosterone secretion and impairing renal potassium excretionCorrect answer
- BLisinopril competitively inhibits potassium secretion in the proximal tubule while causing direct tubular damage that reduces overall nephron function
- CLisinopril increases angiotensin II levels through negative feedback, which paradoxically promotes glomerular hyperfiltration and hyperkalemia through increased renin release
- DLisinopril activates the sympathetic nervous system, causing intense vasoconstriction of the afferent arteriole and simultaneous stimulation of the collecting duct to reabsorb potassium
- ELisinopril blocks bradykinin degradation, causing vasodilation of the efferent arteriole and hyperkalemia through direct inhibition of Na-K-ATPase
- FLisinopril inhibits prostaglandin synthesis in the kidney, reducing renal perfusion and promoting kaliuresis through increased loop of Henle activity
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