Characteristics of Antithyroid Drug-Induced Agranulocytosis in Patients with Hyperthyroidism: A Retrospective Analysis of 114 Cases in a Single Institution in China Involving 9690 Patients Referred for Radioiodine Treatment Over 15 Years.

Abstract

Antithyroid drug (ATD)-induced agranulocytosis is a rare but life-threatening disease. Clinical features of ATD-induced agranulocytosis and outcomes remain incompletely understood. Patients with clinically diagnosed ATD-induced agranulocytosis were retrospectively studied, involving 9690 patients who were referred for radioiodine treatment during a 15-year period (2000-2015) in China. There were 114 cases of agranulocytosis attributable to ATD included, and their clinical characteristics and therapy outcomes were analyzed. The female-to-male ratio of ATD-induced agranulocytosis was 10.4:1. The mean age (±standard deviation) of the patients with ATD-induced agranulocytosis was 41.7 ± 12.3 years. The methimazole and propylthiouracil doses given at the onset were 22.9 ± 8.0 mg/day and 253.6 ± 177.5 mg/day, respectively. ATD-induced agranulocytosis occurred in 45.1%, 74.3%, and 88.5% of patients within 4, 8, and 12 weeks of the onset of ATD therapy, respectively. Fever (78.9%) and sore throat (72.8%) were the most common symptoms when agranulocytosis was diagnosed. The mean recovery time of agranulocytosis was 13.41 ± 7.14 days. Recovery time in the granulocyte colony-stimulating factor (G-CSF)-treated group (12.7 ± 6.0 days) did not differ from that in the group not treated with G-CSF (16.4 ± 10.6 days; p = 0.144). Treatment with (131)I was successful in 87/98 patients (88.8%). The success rate of (131)I was equivalent (p = 1.000) between the groups receiving methimazole (88.2%, 75/85) and propylthiouracil (92.3%, 12/13). This largest single-institution study in China shows that ATD-induced agranulocytosis tends to occur within the first 12 weeks after the onset of ATD therapy. For patients with ATD-induced agranulocytosis, G-CSF does not improve the recovery time of agranulocytosis, and (131)I is an optimal treatment approach.