Thrombocytopenia after Long-Term Use of Low-Dose Methimazole

Although MMI has been reported to cause thrombocytopenia and bleeding, isolated thrombocytopenia due to MMI is quite rare in the literature. This case shows the development of thrombocytopenia in a patient treated with low-dose MMI. Since the patient was euthyroid and this side effect occurred after long-term use of low-dose MMI, it can be assumed that it is a direct toxicity due to dose accumulation of the drug over years or due to immunological mechanisms.