Acute Kidney Injury USMLE Step 1 Practice Question
A 58-year-old man undergoes elective abdominal aortic aneurysm repair. Postoperatively, he develops oliguria with BP 102/64 mmHg, HR 98/min, and serum creatinine 2.9 mg/dL (baseline 0.9 mg/dL). Urinalysis reveals muddy brown granular casts. Serum potassium is 5.8 mEq/L. Renal ultrasound shows no hydronephrosis or renal artery stenosis. Urine sodium is 58 mEq/L with FENa of 3.2%. Which of the following is the most likely etiology of his acute kidney injury?
Answer choices
- ACholesterol embolization from aortic manipulation
- BPostoperative sepsis-related glomerulonephritis
- CContrast-induced nephropathy from preoperative angiography
- DPrerenal azotemia from inadequate fluid resuscitation
- EIschemic acute tubular necrosis from aortic cross-clampingCorrect answer
- FRhabdomyolysis-induced acute kidney injury from surgical positioning
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.