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 hypothyroidism. Three hundred fifty-five patients with diffuse toxic goitres were treated and have been under review for an average of 49.4 months: 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 to 56.0 mCi), and the lowest incidence of hypothyroidism (23%) was in the group that received between 6.0 and 10.5 mCi. Sixty-three percent of the patients whose initial does was greater than 20.0 mCi 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 ¹³¹I has stood the test of time, we believe that ¹³¹I is the radionuclide of choice for the routine treatment of hyperthyroidism.