Which drugs are used as urate-lowering therapy in TLS prophylaxis?

• A. Aggressive hydration alone
• B. Rasburicase alone
• C. Allopurinol or Rasburicase
• D. Dialysis

Answer: (C)

Urate-lowering therapy in TLS prophylaxis aims to prevent uric acid buildup from rapid tumor cell breakdown. Allopurinol works by inhibiting xanthine oxidase, which reduces the production of uric acid, helping prevent uric acid from forming in the first place. Rasburicase takes a different approach by actively degrading existing uric acid into a more soluble compound (allantoin), which is then easily excreted. Because TLS risk centers on uric acid causing kidney irritation or obstruction, using either drug helps protect the kidneys when chemotherapy is given. Aggressive hydration supports urine flow but doesn’t lower urate levels, and dialysis is reserved for established renal failure or refractory cases, not routine prophylaxis. Thus, the appropriate urate-lowering strategies are allopurinol or rasburicase.