Which measure is essential to promote clearance of methotrexate during high-dose therapy?

• A. Adequate hydration and urine output monitoring.
• B. Rapid diuresis with high-dose diuretics only.
• C. No hydration.
• D. Fluid restriction.

Answer: (A)

Methotrexate at high doses is cleared mainly by the kidneys, so keeping the kidneys strongly hydrated and monitoring urine output is essential to promote its elimination. Adequate hydration increases urine volume, which helps flush MTX through the renal tubules and reduces the risk of MTX precipitation and nephrotoxicity. Watching urine output ensures you’re achieving the desired flow and can signal if clearance isn’t proceeding as expected, prompting timely adjustments. Using diuretics to force rapid diuresis isn’t a standard approach and can cause electrolyte problems without guaranteeing better clearance. Fluid restriction or no hydration would impede elimination and raise toxicity risk.