Methimazole Increases Body Weight in Graves’ Disease Patients Reaching Euthyroidism

Graves' disease (GD) is one of the most common autoimmune diseases that cause hyperthyroidism. One of the standard therapies for GD is the antithyroid drug, methimazole (MMI). The goal of GD therapy is to achieve euthyroidism in the patient. Hyperthyroid therapy is often associated with weight gain. This study aimed to determine the effect of MMI administration on weight changes in GD patients who reached euthyroidism. This retrospective cohort study was conducted using the Borneo Wetland Study on Thyroid 2 (BEST-T2) database belonging to the endocrine clinic of the internal medicine department at Ulin Hospital Banjarmasin. We collected data from 58 GD patients. Data were analyzed using the paired t-test with SPSS version 23 software with a confidence level of 95%. The majority of Graves' disease (GD) patients who achieved euthyroid status after receiving methimazole (MMI) were women, with an average age of 40 ± 11.6 years, an initial TSH level of 0.38 (0.004) IU/ml, and an initial FT4 level of 25.41 (16.51) pmol/l. The duration to reach euthyroid status in GD patients after MMI administration was 16 ± 13.4 months. This study showed a significant change in body weight before MMI treatment (53.69 ± 8.2 kg) compared to after MMI treatment (59.41 ± 8.6 kg) with 5.72 kg weight changes in GD patients who reached euthyroidism at Ulin Hospital Banjarmasin (p<0.001). MMI treatment influences weight changes significantly in GD patients reaching euthyroidism.