Effects of short-term potassium iodide treatment for thyrotoxicosis due to Graves disease in children and adolescents

PURPOSE Graves disease is the most common cause of hyperthyroidism in children. Inorganic iodide has been used in combination with antithyroid drugs for more effective normalization of thyroid hormones in some cases of severe thyrotoxicosis. This study aimed to investigate clinical characteristics of childhood thyrotoxicosis and effectiveness of inorganic iodide in the early phase of treatment. METHODS Sixty-seven pediatric patients (53 girls/14 boys, 11.1±3.4 years of age), with newly diagnosed thyrotoxicosis due to Graves disease were recruited. Forty-nine patients were treated with antithyroid drugs alone, while 18 patients were treated with combination of antithyroid drugs and potassium iodide. Initial thyroid function tests and levels of thyroid antibodies were recorded for all patients. Thyroid function tests were repeated 2 and 8 weeks after the initiation of treatment. Measurement thyroid antibodies were done 8 weeks after the initiation of treatment. RESULTS Mean triiodothyronine and free thyroxine levels were significantly lower (P<0.05) in the group receiving combined therapy of antithyroid drugs and potassium iodide after 2 weeks of treatment compared to the patients receiving antithyroid drugs alone. Eight weeks after the initiation of treatment, thyroid function tests in the two groups did not show significant differences. CONCLUSION The use of potassium iodide in combination with antithyroid drug is effective for more rapid normalization of thyroid hormones in the early phase treatment of childhood thyrotoxicosis, but larger studies with adequate power are needed in future.