Time course to hypothyroidism after fixed-dose radioablation therapy of Graves' disease in children.

Abstract

To characterize the development of hypothyroidism in pediatric patients who receive a fixed dose of radioactive iodine (RAI). Medical records of children treated with fixed-dose RAI for Graves'disease between 1993 and 2001 were reviewed. Multiple variables including sex, age, thyroid hormone levels, thyroid-stimulating immunoglobulin titer, antithyroid medication use, and 24-hour radioiodine uptake were investigated as possible predictive factors for the development of hypothyroidism after treatment. All patients received RAI at a dose of between 13.8 and 15.6 mCi (average, 14.7 mCi; SD, 0.5). Permanent hypothyroidism developed in all 40 patients, although a second dose of RAI was required in one case. The average time to hypothyroidism was 77 days (SD, 32), with a range of 28 to 194 days; 75% of the patients were diagnosed with hypothyroidism between 40 and 90 days. RAI treatment was ineffective in an additional patient, who required subtotal thyroidectomy. We conclude that a fixed dose of RAI is effective therapy in nearly all pediatric patients with Graves'disease. Factors predicting the time course to hypothyroidism were not identified.