Fatal intoxication caused by conventional-dose methotrexate in an elderly patient with end-stage renal disease: A...

Methotrexate (MTX) is a first-line agent for rheumatoid arthritis, and impaired renal excretion drastically elevates the risk of fatal drug accumulation. End-stage renal disease (ESRD) patients face an extreme toxicity risk even under conventional low-dose MTX, yet related fatal cases remain underreported. This case highlights critical clinical warnings for rheumatologists and emergency physicians.

A 71-year-old male with a 5-year history of rheumatoid arthritis and 1-year untreated chronic kidney disease stage 5 received weekly 10 mg subcutaneous MTX for 3 consecutive weeks without folic acid supplementation or regular laboratory monitoring. One day after his latest injection, he developed persistent nausea, vomiting, extensive oral ulcers, a skin rash, and drowsiness.

Severe MTX intoxication complicated by profound bone marrow suppression, septic shock, and multiple organ dysfunction syndrome. Persistently elevated serum MTX confirmed impaired renal drug clearance in ESRD.

Immediate MTX discontinuation, leucovorin calcium rescue, continuous renal replacement therapy, broad-spectrum anti-infection treatment, blood product transfusion, and invasive mechanical ventilation for progressive circulatory and respiratory failure.

Serial serum MTX remained elevated 6 days after the final dose. Despite full intensive supportive care, the patient died of refractory septic shock and irreversible multiorgan failure.

Conventional-dose MTX is contraindicated for ESRD patients. Mandatory pre-prescription renal function assessment, regular laboratory monitoring, and folate supplementation are essential to prevent life-threatening MTX toxicity in high-risk elderly populations.