Long-term follow-up of an infant with thyrotoxicosis due to germline mutation of the TSH receptor gene (Met453Thr)

A 18-year clinical follow-up period in a male patient with a germline TSH-R gene mutation (Met453Thr) is described. Nonautoimmune thyrotoxicosis was d iagnosed at the age of 7 months. The patient had exophthalmus, failure to t hrive, advanced bone age and no goiter. Longterm antithyroid drug treatment (ATD) was necessary during childhood. At the age of 7 years he developed a goiter. Subtotal thyroidectomy was performed at the age of 9 years, follow ed by repeated ablative radiotherapy at the age of 9.5-13 years due to a to xic multinodular goiter. After 13 years ATD could be discontinued and the p atient was euthyroid until 16 years of age, where L-thyroxine substitution had to be started. The exophthalmus diminished, and had disappeared at the age of 18 years, when CT scan of the orbit was performed. Conclusion: TSH-R mutation must be considered in early nonautoimmune thyrotoxicosis. A very agressive treatment strategy is necessary.