125I Therapy in Graves' Disease

Abstract

Because of the physical and radiobiologic differences between 125I and 131I, a trial using 125I to treat hyperthyroidism was undertaken in the hope of controlling hyperthyroidism without causing subsequent hypothyrodism. Patients (355) with diffuse toxic goiters were treated and were under review for an average of 49.4 mo.: 63.4% are euthyroid, 33.5% are hypothyroid and 3.1% remain hyperthyroid. Different groups of patients received a wide range of doses of 125I (4.0-56.0 mCi), and the lowest incidence of hypothyroidism (23%) was in the group that received between 6.0-10.5 mCi. Of the patients whose initial does was greater than 20.0 mCi, 63% are hypothyroid. Persistent hyperthyroidism was common in patients who received small doses. Because of the high incidence of posttreatment hypothyroidism in this series and because 125I had stood the test of time, 131I is apparently the radionuclide of choice for the routine treatment of hyperthyroidism.