Chronic Kidney Disease USMLE Step 1 Practice Question
A 72-year-old man with hypertension develops oliguria after prolonged hypotension (BP 78/52 mmHg) during septic shock. Over 48 hours, serum creatinine rises from 1.2 to 4.8 mg/dL, and urine output decreases to 180 mL daily. Urinalysis reveals muddy brown granular casts and fractional excretion of sodium of 3%. Urine microscopy shows no proteinuria. He takes lisinopril chronically. Which nephron segment is most vulnerable to this ischemic injury?
Answer choices
- ADistal convoluted tubule and glomerulus
- BPodocytes and mesangial cells
- CCollecting duct and macula densa
- DAfferent arteriole and proximal convoluted tubule only
- EProximal tubule and thick ascending limbCorrect answer
- FThin descending and thin ascending limbs of loop of Henle
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