Remission of Graves' disease is not related to early restoration of euthyroidism with high-dose methimazole therapy

Introduction and aims: The most recent hypothesis postulated that early restoration of euthyroid state in patients with Graves' disease changes the course of the disease and leads to better disease control. Therefore, we analyzed the efficacy of methimazole therapy and the course of disease in patients with restored euthyroidism and in patients with active disease on first control visit. Patients and methods: We included 63 patients with total T4 level >190 nmol/L or T3 >7 nmol/L and diffuse goiter with no previous episodes of hyperthyroidism. All patients received initially high doses of methimazole (60-80 mg) followed by a rapid dose reduction. Results: Ten percent of patients were excluded from the study due to side effects. Two different groups emerged after 5 weeks of treatment with same dose of methimazole: group 1 with active disease (48%) and group 2 with restored euthyroidism. Further controls on 12th, 24th and 68th weeks of treatment showed no difference in remission rates, number of iatrogenic hypothyroid episodes, and number of exacerbations between the two groups, regardless of methimazole dose. There was no association between age, gender, thyroid hormone levels, and remission and exacerbation rates. Conclusions: Initially, higher methimazole doses with rapid progressive decrease to maintenance dose result in similar remission rates and are followed by similar incidence of adverse side-effect as fixed low dose therapy. Our results indicate that neither an early restoration of euthyroidism nor the difference in methimazole doses influence the course of Graves' disease.