Which statement correctly describes the action of rasburicase in tumour lysis syndrome?

• A It inhibits xanthine oxidase and reduces new uric acid synthesis
• B It chelates phosphate released from lysed tumour cells
• C It alkalinizes the urine to increase urate solubility
• D It converts preformed uric acid to the soluble metabolite allantoin ✓

Explanation

Rasburicase is recombinant urate oxidase that catalyses oxidation of already formed uric acid to allantoin, which is far more soluble and renally excreted, so it both lowers and prevents hyperuricaemia rapidly. Allopurinol only blocks xanthine oxidase, preventing new urate formation without clearing existing uric acid, and it accumulates xanthine. Urinary alkalinization is no longer recommended because it promotes calcium phosphate precipitation. Phosphate is managed with hydration and phosphate binders.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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