Acute Kidney Injury USMLE Step 1 Practice Question
A 45-year-old woman with no prior medical history presents to the emergency department 4 hours after a motor vehicle accident with crush injuries to both lower extremities. On examination, she has severe swelling and bruising of both legs with preserved distal pulses. Vital signs show HR 112 bpm, BP 95/58 mmHg, RR 22/min. Laboratory studies reveal: serum creatinine 3.2 mg/dL (baseline 0.9 mg/dL), BUN 48 mg/dL, potassium 6.1 mEq/L, urine color dark brown. Urinalysis shows specific gravity 1.035, dipstick positive for blood with 0 RBCs on microscopy, and positive myoglobin. Urine osmolality is 620 mOsm/kg. Which of the following is the most appropriate immediate intervention?
Answer choices
- AInitiate hemodialysis for acute hyperkalemia management
- BAdminister aggressive intravenous hydration with normal saline and target urine output 200-300 mL/hourCorrect answer
- CAdminister sodium bicarbonate 1-2 mEq/kg IV to alkalinize urine
- DAdminister furosemide 40 mg IV to promote diuresis and reduce fluid overload
- EPerform bilateral fasciotomy to decompress leg compartments
- FAdminister mannitol 1 g/kg IV bolus to increase glomerular filtration rate
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