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Acute tubular necrosis after sepsis — RACP Adult Medicine MCQ

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HardNephrologyAcute tubular necrosis after sepsisRACP Adult Medicine

A 64-year-old man is recovering from septic shock due to pneumonia. Creatinine rises from 85 to 260 micromol/L over 48 hours. Urine sodium is high, fractional excretion of sodium is 3.2%, and urine microscopy shows muddy brown granular casts. Renal ultrasound is normal. What is the most likely cause?

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Correct answer: A — Ischaemic acute tubular necrosis

Shock followed by intrinsic AKI with high urinary sodium and muddy brown casts is typical of acute tubular necrosis. Simple pre-renal azotaemia usually has avid sodium retention and no granular casts. Obstruction is excluded by ultrasound, and the other diagnoses do not match the acute septic context.

Reference: Kidney Health Australia AKI guidance; AMH