What urine output rate is targeted to help prevent methotrexate-related nephrotoxicity?

• A. 1-1.5 mL/kg/hour
• B. 2-3 mL/kg/hour
• C. 4-5 mL/kg/hour
• D. 0.5 mL/kg/hour

Answer: (B)

Keeping the kidneys safe during high-dose methotrexate hinges on making sure the drug and its metabolites stay in solution and are flushed out promptly. The best way to support that is to maintain brisk urine flow, along with urine alkalinization, so MTX doesn’t precipitate in the renal tubules and cause nephrotoxicity. A urine output target of about 2–3 mL per kilogram per hour provides enough flow to dilute MTX and promote efficient clearance without overloading the patient with fluids. Values lower than this raise the risk of MTX crystallization and kidney injury, while substantially higher rates aren’t usually necessary and can lead to fluid overload. In practice, this 2–3 mL/kg/hour target is the standard balance used during high-dose MTX treatment, paired with close monitoring of MTX levels and supportive measures like hydration and urine alkalinization.