Acute Kidney Injury USMLE Step 1 Practice Question
A 68-year-old man with hypertension presents with acute dyspnea and orthopnea. Vital signs: BP 168/95 mmHg, HR 110/min, RR 22/min, SpO2 88% on room air. He takes lisinopril but reports medication non-adherence for 2 weeks. Serum creatinine is 2.8 mg/dL (baseline 1.0), and urinalysis shows no proteinuria. Elevated angiotensin II causes marked efferent arteriolar constriction with modest renal plasma flow decrease. Which physiologic change occurs initially?
Answer choices
- AComplete loss of autoregulation
- BDecrease in filtration fraction
- CNo change in glomerular filtration rate
- DIncrease in urine pH only
- EIncrease in filtration fractionCorrect answer
- FDecrease in glomerular filtration pressure with resultant decline in GFR
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