A 16-year-old boy starts induction chemotherapy for Burkitt lymphoma. Twelve hours later: potassium 6.6 mEq/L, phosphate 9.2 mg/dL, calcium 5.6 mg/dL, uric acid 16 mg/dL, creatinine 2.8 mg/dL. He is haemodynamically stable with good urine output. Along with aggressive hydration, which agent directly addresses the main driver of his acute kidney injury?

• A Allopurinol 300 mg daily
• B Sodium polystyrene sulfonate orally
• C Rasburicase, recombinant urate oxidase ✓
• D Calcium gluconate infusion repeated 4-hourly

Explanation

Tumour lysis syndrome causes acute uric acid nephropathy when uric acid precipitates in acidic tubular fluid, obstructing tubules. Rasburicase converts uric acid to the soluble metabolite allantoin and rapidly lowers urate levels, making it preferred in established hyperuricaemia with renal involvement. Allopurinol only prevents new uric acid formation and does not lower preformed urate, so it suits prophylaxis rather than established severe disease. Calcium gluconate treats cardiac effects of hypocalcaemia and hyperkalaemia but leaves the renal insult untouched.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.