Successful rescue with leucovorin and thymidine in a patient with high-dose methotrexate induced acute renal failure.

A 54-year-old patient with primary cerebral lymphoma was treated with two 4-weekly cycles of high-dose intravenous cytarabine (12 g/m2) and methotrexate (3 g/m2). The administration of the first course proceeded without notable complications. Before the administration of methotrexate in the second cycle blood cell counts and chemistry showed no abnormalities except for slightly increased alkaline phosphatase and gamma-glutamyl-transpeptidase levels which was attributed to diphantoin comedication. The patient developed symptoms of acute renal failure 7 h after methotrexate infusion which resulted in a very high serum methotrexate level (39.84 micromol/l) at 20 h after infusion. Rescue therapy was intensified: the leucovorin dosage was increased (1,200 mg continuous i.v. infusion every 24 h) and combined with thymidine rescue therapy (8 g/m2 per day continuous i.v. infusion every 24 h). Urine alkalinization was increased and diphantoin therapy was stopped. Leucovorin eye drops and mouth washes were started 5 days after methotrexate administration to prevent conjunctivitis and mucositis as a result of high methotrexate levels (>2.4 micromol/l). In spite of the fact that serum methotrexate levels remained persistently higher than 0.1 micromol/l for 12 days, the patient experienced no further short-term systemic toxicity except for anaemia (grade 3 according to NCI Common Toxicity Criteria). After day 12 intensified rescue therapy and the frequency of alkalinization were decreased to standard procedures and stopped on day 19. It is concluded that i.v. administration with high-dose methotrexate can result in unpredictable acute toxicity. In our patient, acute methotrexate toxicity was treated successfully by intensification of classical leucovorin rescue therapy in combination with thymidine infusion. In addition, leucovorin mouth washes and eye drops may have prevented mucositis and conjunctivitis, respectively.