Why is hydration important in TLS prophylaxis?

• A. To maintain renal perfusion and promote excretion of uric acid and electrolytes, reducing kidney injury risk.
• B. To increase uric acid production.
• C. To promote kidney injury.
• D. To cause diuresis with no effect.

Answer: (A)

Hydration protects the kidneys during TLS prophylaxis by ensuring good renal perfusion and high urine output, which helps clear uric acid and electrolytes released when tumor cells break down. In tumor lysis, rapid cell death dumps nucleic acids into the bloodstream, metabolizing to uric acid that can crystallize in renal tubules and cause acute kidney injury. Adequate IV fluids keep urine production up, dilute the urine, and promote excretion of uric acid, potassium, and phosphate, reducing the risk of crystal obstruction and kidney damage. This is why hydration is a foundational part of TLS prevention. Increasing uric acid production would worsen the problem, promoting kidney injury is exactly what hydration aims to prevent, and diuresis that doesn’t improve clearance wouldn’t provide renal protection.