[Development of Basedow disease after radioiodine therapy for nodular goiter]

It has been observed in the past few years, that radioiodine therapy triggers autoimmune thyrotoxicosis. The possible mechanism of this phenomenon is that protein fragments enter the circulation after thyroid cell damage induced by radiation. TSH-receptor autoantibodies are produced in genetically susceptible patients after radiotherapy. In treating nodular goiter--a non-immune thyroid disease--with 131I, an immunogenic disorder--Basedow-Graves' disease--may develop. The authors present this phenomenon in a case of a 67 year-old woman with a history of operation for euthyroid nodular goiter in 1977. In November 2001, she was admitted to the hospital with local signs and symptoms of relapse of euthyroid nodular goiter (TSH-receptor antibodies were not detected). She was treated with oral doses of 320 MBq of radioiodine to reduce the thyroid volume. Four months after radioiodine therapy the patient had developed signs of thyrotoxicosis. At that time TSH-receptor antibodies were found to be positive. Thyreostatic therapy was administered and still being in use till today. The authors draw the attention to the fact that, when a hyperthyrosis develops after radioiodine therapy of a non-immune thyroid disease, the possibility of Graves-Basedow disease should be raised, especially in a patient with a positive family history.