RESUMEN
RATIONALE: Low-dose methotrexate has a relatively good safety profile. However, in cases where patients with multiple risk factors, a delayed excretion has been observed, resulting in the occurrence of severe adverse reactions. It is necessary to supervise and intervene throughout the entire process of treating patients with multiple risk factors for methotrexate, and to strengthen the rational application of methotrexate. PATIENT CONCERNS AND DIAGNOSES: A 66-year-old male patient was admitted to our hospital with rheumatoid arthritis and underlying conditions such as chronic obstructive pulmonary disease (COPD). This patient received treatment with low-dose MTX (10 mg/week) and experienced adverse reactions including anemia. He was diagnosed with methotrexate-induced bone marrow suppression. INTERVENTIONS AND OUTCOMES: The therapeutic drug monitoring revealed that the serum drug concentration of methotrexate was at a critical level and the patient was rescue with calcium folinate and other adjuvant therapy such as transfusions of red blood cells, plasma, platelets, oral Yixuesheng tablets and Leucogen tablets. We conducted a 1-month follow-up, and there was no recurrence of bone marrow suppression and anemia. LESSONS: To ensure rational administration of methotrexate, it is important to fully evaluate the clinical manifestations and physical condition of patients and regularly detecting the serum drug concentration of methotrexate when patients with multiple risk factors, Otherwise, even low-dose methotrexate administration may cause delayed excretion, resulting in severe adverse reactions.