High Dose 131 I Therapy for the Treatment of Hyperthyroidism Caused by Graves’ Disease

Abstract

Radioactive iodine (131I) has become the most widely used therapy for patients with hyperthyroidism caused by Graves’ disease in the United States. There remains, however, significant variability among 131I dosing regimens, and it is clear that most patients ultimately develop hypothyroidism after therapy. To avoid persistent hyperthyroidism, we adopted a high dose 131I therapy protocol based on measurement of 24-h thyroid 123I uptake designed to deliver 8 mCi (296 MBq) to the thyroid gland 24 h after 131I administration. To evaluate the efficacy of this protocol, we reviewed our clinical experience over a 7-yr period. We treated 261 patients (219 women and 42 men) with hyperthyroidism caused by Graves’ disease with 131I [mean dose, 14.6 mCi (540 MBq)] between 1993 and 1999. Before treatment, 207 (79%) had received an antithyroid drug (109 propylthiouracil and 98 methimazole). We determined their thyroid status 1 yr after treatment in relation to age, pretreatment with an antithyroid drug, pretreatment th...