Nephrotoxicity due to intermediate-dose methotrexate without rescue in an obese adolescent with acute lymphoblastic leukemia.

Toxicity from intermediate-dose methotrexate (MTX) is unusual. A severely obese adolescent with acute lymphoblastic leukemia experienced significant, delayed nephrotoxicity from intermediate-dose MTX. Altered MTX disposition may occur as a consequence of other ingestions or conditions such as obesity.