Hyperthyroid Graves’ disease after radioiodine therapy for non-toxic multinodular goiter

ABSTRACT

Background: Radioiodine treatment has been used to reduce the size of euthyroid multinodular goiter (MNG) as an alternative to surgery. Postradioiodine Graves’ disease is a rare side effect which can occur several months after radioiodine treatment for non-toxic multinodular goiter. Objective: To report two patients who developed hyperthyroid Graves’ disease after radioiodine therapy for non-toxic multinodular goiter. Methods: We report the clinical and laboratory findings of Graves’ disease which occurred after radiotherapy. The literature was reviewed for the incidence and pathogenesis of Graves’ disease after radioiodine therapy. Results: The first case describes a 39-year-old woman presented with hyperthyroidism after repeated radioiodine therapy for non-multinodular goiter. The second case describes a 45-year-old woman who presented with hyperthyroidism after the first dose of radioiodine therapy for non-multinodular goiter. Graves’ disease was confirmed in both cases by the presence of thyrotropin receptor antibody (TRAb). Both patients respond well to methimazole. Conclusion: We demonstrate the rare occurrence of Graves’ disease as the side effect of radioiodine treatment for non-toxic multinodular goiter. They highlight the importance of recognizing patients with hyperthyroidism after radioiodine treatment as they could develop hyperthyroid Graves’ disease following this treatment.