Results of radioiodine treatment in various types of hyperthyroidism

During an investigation period starting early in 1982 and ending in the middle of 1985 a total of 360 patients were treated with iodine-131 for hyperthyroidism of different origins. The case reports of 337 of these patients were reviewed for the purposes of this study. The patients were divided into three groups. In this cohort, the healing rates achieved with one single treatment were 84.4% for autonomic adenomas, 50.8% for hyperthyroidism of other than immunologic origins and 22.7% for Basedow's disease. After a series of up to four treatments the healing rates were seen to be increased to 93% for autonomous adenomas, 84% for nonimmunogenic hyperthyroidism and 80% for Basedow's disease. The results thus achieved appeared to be unrelated to the patients' sex or previous surgical interventions for disorders of the thyroid. The findings show that therapeutic regimes calculated individually on the basis of a formula should be approached with some caution. Thus, doses lower than 100 Gy are hardly advisable for patients showing diffuse hyperthyroidism. It would also appear wise in autonomous adenomas to reduce the dose from 400 to 200 Gy. Likewise, the use of doses above 15 mCi should be restricted to special cases. A dose-effect relationship could not be detected in patients suffering from Basedow's disease. It seems recommendable here to use low initial doses so as to permit less radiosensitive patients to be healed by repeat treatment with a higher dose. (orig./MG)