A case of antithyroid drug-induced agranulocytosis from a second antithyroid drugs (ATD) administration in a relapsed Graves' disease patient who was tolerant to the first ATD treatment

[Adverse reactions of methimazole in children with hyperthyroidism]

OBJECTIVES

To investigate the incidence rate of adverse reactions of methimazole in children with hyperthyroidism.

METHODS

A retrospective analysis was performed on the medical data of 304 children with hyperthyroidism who were hospitalized in Shengjing Hospital of China Medical University from January 2015 to May 2021. The incidence rate of methimazole-related adverse reactions was analyzed. The risk factors for common adverse reactions were evaluated.

RESULTS

Among the 304 children, 87 (28.6%) experienced adverse reactions, among whom there were 20 boys (23%) and 67 girls (77%). Common adverse reactions included neutropenia (12.8%), rash (11.8%), elevated alanine aminotransferase (9.5%), and joint pain (3.0%), and some children experienced multiple adverse reactions simultaneously or intermittently. Neutropenia often occurred within 3 months after administration (25/39, 64%), elevated alanine aminotransferase often occurred within 1 month after administration (17/29, 59%), and rash often occurred within 3 months after administration (30/36, 83%). Most of the above adverse reactions returned to normal after symptomatic treatment. The multivariate logistic regression analysis showed that younger age and lower absolute neutrophil count before treatment were risk factors for neutropenia after methimazole treatment (P<0.05).

CONCLUSIONS

The adverse reactions of methimazole are common in children with hyperthyroidism, and most adverse reactions occur within 3 months after administration and can be relieved after symptomatic treatment. Children with a younger age or a lower baseline absolute neutrophil count may have a higher risk of neutropenia.