Agranulocytosis is a rare but serious adverse drug reaction (ADR) of thionamide antithyroid drugs (ATDs). We explored the characteristics of ADRs in patients with hyperthyroidism.
This retrospective study included 3558 inpatients with Graves’ disease (GD) treated in a Class A Grade 3 hospital between 2015 and 2019. The clinical presentation and laboratory workup of patients with ATD-induced agranulocytosis were analyzed.
Agranulocytosis was thought to be caused by ATD in 36 patients. The hospital length of stay (h-LOS) was 12 (10-16) days, and hospitalization costs were approximately $2810.89 (2156.50-4164.67). The median duration of ATD therapy prior to agranulocytosis development was 30 (20-40) days. Fever (83.33%) and sore throat (75%) were the most common symptoms as early signs of agranulocytosis. The lowest neutrophil counts were 0.01 (0.00-0.03) × 10/L and 0.14 (0.02-0.29) × 10/L in the methimazole and propylthiouracil groups, respectively (P = 0.037). The recovery times of agranulocytosis were 9.32 ± 2.89 days and 5.60 ± 4.10 days in the methimazole and propylthiouracil groups, respectively (P = 0.016). Severe agranulocytosis patients required a longer time to recover (P <0.001) and had closer to normal serum thyroxine (T4) and triiodothyronine (T3) concentrations. The interval between the first symptom of agranulocytosis and ATD withdrawal was 1 (0-3) day.
Agranulocytosis patients needed a long h-LOS and incurred high costs. Methimazole was prone to causing more serious agranulocytosis than propylthiouracil. High thyroid hormone was unlikely to play a role in the ADR. Patient education is important.

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