Antithyroid drug-induced agranulocytosis: report of 13 cases.

BACKGROUND Antithyroid drug (ATD)-induced agranulocytosis is rare but may cause fatal complications in patients with thyrotoxicosis during treatment with thionamide-derived drugs. From our previous experience, we note that 2 of 11 such patients died in a 10-year retrospective study. METHODS We reviewed thirteen patients who developed agranulocytosis from 7,466 patients with hyperthyroidism while they were being treated with ATD from July 1989 to November 2003. RESULTS The incidence of ATD-induced agranulocytosis (absolute neutrophil counts < 500/mm3) was 0.17%. The age of the 13 patients (female: male = 10:3) was 28 to 61 years (mean +/- SD: 39.6 +/- 10.0 years). The most common clinical manifestations were fever (100%), sore throat (76.9%) and chills (46.1%). At the time of agranulocytosis attack, ATD had been administered for 12 to 66 days (mean +/- SD: 36.4 +/- 18.7 days) and the duration of symptoms was 1 to 14 days (mean +/- SD: 4.6 +/- 3.7 days). Intravenous infusion of 300 microg granulocyte colony-stimulating factor (G-CSF) per day was administered to 3 patients simultaneously with intravenous empirical broad-spectrum antibiotics. After intensive and supportive treatment in hospital, all the patients recovered with absolute neutrophil counts of more than 500/mm3 in 2 to 13 days (mean +/- SD: 7.6 +/- 3.4 days). CONCLUSIONS In our 25-year clinical experience, the most cost-effective method of managing agranulocytosis induced by thionamide-derived ATD is that all patients with thyrotoxicosis must be warned that their white blood cells and differential counts should be checked immediately whenever the "common cold" symptoms occur during treatment, especially within the first 3 months of medication.