The treatment of hyperthyroidism with iodine-131

Abstract

Uncertainty about the use of radioiodine in the treatment of thyrotoxicosis has been raised by recent publicity on irradiation thyroid carcinogenesis. Data are reviewed from the publications of the Cooperative Thyrotoxicosis Follow-up Study of 22,000 patients treated with 131 I and 14,000 patients treated surgically or solely with antithyroid drugs or surgery. No increased incidence of leukemia has occurred in 30 years of therapy. Although large tracer doses of 131 I may prove to be carcinogenic, the therapeutic doses used to treat hyperthyroidism appear to decrease the incidence of carcinoma by preventing thyroid cell replication. These is considerable evidence from the Atom Bomb Casualty Commission and from recent data on the treatment of hyperthyroidism and thyroid cancer with 131 I in children that treatment doses of 131 I have not produced abnormal fertility or birth histories. The yearly cumulative incidence of hypothyroidism after the first year of treatment with 131 I of 2.7%, as compared to 1.8% after surgery, is not decisive in affecting the choice of treatment. The published considerably higher morbidity and mortality from surgical thyroidectomy in children as compared to adults has not been generally recognized or discussed with parents. There is growing belief, therefore, that 131 I is the current treatment of choice for thyrotoxicosis in children and adolescents. The persistence of goiter after cure usually signals the presence of coexisting Hashimoto's struma. Radioiodine uptakes tests are being performed more commonly after the diagnosis of thyrotoxicosis and are confirmed with in vitro tests because of the more common presence of self-limited thyrotoxicosis and thyrotoxicosis with normal or subnormal 131 I uptake.