A 16-year-old boy begins induction chemotherapy for T-cell acute lymphoblastic leukaemia with a presenting WBC of 220,000/uL. Twelve hours later he reports nausea and passes minimal urine. Labs: potassium 6.4 mEq/L, uric acid 14 mg/dL, phosphate 8.2 mg/dL, calcium 6.0 mg/dL, creatinine 2.4 mg/dL. Which agent is most appropriate for managing the hyperuricaemia?

• A Furosemide alone
• B Allopurinol
• C Intravenous sodium bicarbonate infusion
• D Rasburicase ✓

Explanation

Established laboratory tumour lysis syndrome with severe hyperuricaemia warrants rasburicase, a recombinant urate oxidase that converts uric acid to soluble allantoin and lowers levels rapidly. Allopurinol inhibits xanthine oxidase and blocks new urate formation but cannot clear urate already present, suiting prophylaxis rather than treatment. Urinary alkalinisation is avoided because it promotes calcium phosphate precipitation, and furosemide alone is insufficient.

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

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