Acute Kidney Injury USMLE Step 1 Practice Question
A 35-year-old man is brought to the emergency department 18 hours after being trapped under a collapsed scaffold at a construction site. He reports severe pain in both legs and dark-colored urine since the accident. On examination, he has significant swelling and bruising of bilateral lower extremities with evidence of muscle necrosis. Vital signs: BP 128/76 mmHg, HR 102 bpm, RR 18/min, temperature 37.2°C. Laboratory studies show: serum creatinine 4.2 mg/dL (baseline 0.9 mg/dL), potassium 6.8 mEq/L, phosphate 7.2 mg/dL, uric acid 11.2 mg/dL, CK 52,000 U/L, and urinalysis with positive myoglobin and muddy brown casts. Which of the following interventions is most critical to prevent further deterioration of renal function?
Answer choices
- AImmediate hemodialysis given the elevated potassium and creatinine levels
- BHigh-dose furosemide (250 mg IV) to increase urine output to >200 mL/hr
- CAggressive intravenous normal saline hydration with concurrent sodium bicarbonate to alkalinize urineCorrect answer
- DSodium polystyrene sulfonate (Kayexalate) to address hyperkalemia and prevent cardiac arrhythmias
- EMannitol osmotic diuresis without alkalinization to flush myoglobin from the collecting ducts
- FSurgical fasciotomy of the affected compartments to relieve rhabdomyolysis
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