A 7-year-old child with bulky T-cell lymphoblastic lymphoma and pretreatment uric acid of 11 mg/dL is to receive induction chemotherapy. Rasburicase is administered before the first dose. Its protective effect comes from:

• A Blocking tubular reabsorption of uric acid
• B Enzymatically converting uric acid to the soluble metabolite allantoin ✓
• C Inhibiting xanthine oxidase to halt new urate formation
• D Alkalinizing the urine to increase urate solubility

Explanation

Rasburicase is recombinant urate oxidase, an enzyme absent in humans, that converts poorly soluble uric acid to allantoin, which is far more water soluble and renally excreted. This rapidly lowers urate before and during tumor lysis. Allopurinol merely prevents new urate formation and does nothing about urate already present, while urinary alkalinization is avoided because it promotes calcium phosphate deposition. Rasburicase is contraindicated in G6PD deficiency since hydrogen peroxide generated during catalysis triggers hemolysis.

Reference: Nelson Textbook of Pediatrics, 22nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.