Acute Kidney Injury USMLE Step 1 Practice Question
A 68-year-old man with newly diagnosed multiple myeloma presents to the emergency department with fatigue, nausea, and a 3-day history of decreased urine output. He started bortezomib-based chemotherapy 5 days ago. Physical examination reveals no edema or signs of volume depletion. Vital signs are stable. Laboratory studies show: serum creatinine 3.2 mg/dL (baseline 0.9 mg/dL), BUN 48 mg/dL, sodium 138 mEq/L, potassium 5.2 mEq/L, calcium 10.2 mg/dL. Urinalysis shows dipstick-positive protein (3+), and urine microscopy reveals granular casts and free light chains. The fractional excretion of sodium (FENa) is 0.8%. Renal ultrasound shows normal-sized kidneys without hydronephrosis. Which of the following is the most likely diagnosis?
Answer choices
- AAcute interstitial nephritis from bortezomib hypersensitivity
- BPrerenal azotemia from volume depletion
- CLight chain cast nephropathy (myeloma kidney)Correct answer
- DContrast-induced nephropathy
- EAcute tubular necrosis from sepsis
- FPost-infectious glomerulonephritis
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