Methimazole-induced agranulocytosis treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF): a case report.

Methimazole 5 mg three times daily was prescribed in 1994 spring to a woman, aged 53 years, with relapsed hyperthyroidism. The drug was discontinued six weeks after initiation because of leukopenia. Two weeks still later, the patient developed chills, high fever, and a sore throat. The leukocyte count was 1,100/mm3 with 23% granulocytes, 76% lymphocytes and 1% monocytes. The granulocyte count stopped decreasing only three weeks after the drug was discontinued when the recombinant human granulocyte colony-stimulating factor (rhG-CSF) was given; the patient recovered uneventfully. Thus we recommend that the peripheral leukocyte count of patients who receive methimazole therapy must be carefully monitored during the first three months. Furthermore, the use of rhG-CSF for methimazole-induced agranulocytosis abbreviates the period required for marrow recovery after cessation of this offensive drug.