Calcium Folate for Reducing the Side Effects of Low-dose Methotrexate in Rheumatoid Arthritis: A Case Report

Introduction: We reported a patient with rheumatoid arthritis who received chronic methotrexate (MTX) therapy and experienced several adverse reactions like hemocytopenia and renal impairment. Under the monitoring of the therapeutic drug concentration, calcium folate and other measures were used to accelerate methotrexate excretion and eliminate adverse reactions.Case Presentation: A 66-year-old man with rheumatoid arthritis received MTX and developed adverse effects of bone marrow suppression, like pancytopenia. He had a black stool, and he tested positive for occult blood, which was considered gastrointestinal bleeding. The blood MTX concentration reached 4.07 µmol/L, and leucovorin was administered to rescue the patient's life. Besides, hydration and alkaline urine were applied to quickly clear methotrexate inside the body.Conclusion: Low-dose MTX has fewer adverse reactions but may cause bone marrow suppression- related side effects. Blood concentration monitoring can be used to guide the rescue of MTX poisoning.