FUNCTIONAL RESULTS OF RADIOIODINE THERAPY WITH A 300-GY ABSORBED DOSEIN GRAVES-DISEASE

The aim of this study was to assess the results of high-dose radioiodi ne therapy given to 43 patients with recurrent hyperthyroidism due to Graves' disease between 1986 and 1992. We chose an intrathyroidal abso rbed dose of 300 Gy and determined the applied activity individually, which ranged from 240 to 3120 MBq with a median of 752 MBq. Hyperthyro idism was eliminated in 86% of cases after 3 months and in 100% after 12 months. No patient required a second radioiodine treatment. The inc idence of hypothyroidism was 63% after 3 months and 93% after 18 month s. Neither the pretherapeutic thyroid-stimulating immunoglobulin level nor the degree of co-existing endocrine ophthalmopathy was correlated with the time at which hypothyroidism developed. Patients with previo us radioiodine therapy developed hypothyroidism earlier than patients with previous thyroid surgery. The results show that ablative radioiod ine therapy with a 300-Gy absorbed dose is a very effective treatment of hyperthyroidism in Graves' disease, but it should be restricted to patients with recurrent hyperthyroidism combined with severe co-existi ng disorders or episodes of unfavourable reactions to antithyroid drug s.