[Results of radioiodine therapy in different forms of hyperthyroidism in relation to the planned dosage]

The aim of this study was to assess the efficacy of radioiodine therapy (131J) in a large group (n = 925) of hyperthyroid patients treated at two major departments of nuclear medicine (Freiburg, abbr. FR, and Munich, abbr. M). 761 patients suffered from non-immunogenic hyperthyroidism (Plummer's disease) and the remaining 164 patients from immunogenic hyperthyroidism (Graves' disease). In these cases, radioiodine therapy using doses between 60 and 80 Gy proved ineffective, FR (80 Gy) recording 28% success and M (60 Gy) 54%. A dose of 150 Gy, however, is successful in more than 80% of the cases: FR 81%, M86%. However, the incidence rate of hypothyroidism increases consecutively with 150 Gy: FR 49%, M 62%. In patients suffering from Plummer's disease, the solitary autonomous nodule can be eliminated by radioiodine therapy (400 Gy) with a high rate of success (95%); the same applies to multinodular autonomous adenomas. The therapeutic concept applying a dose of 400 Gy to the total functional autonomous tissue (delineated by ultrasound) yields slightly better results (95%) than 150 Gy applied to thyroid gland (M88%, FR82%). This dosimetric compromise is a practicable alternative which is tolerably successful. In patients suffering from disseminated non-immunogenic hyperthyroidism, a dose of 150 Gy applied to the entire organ succeeds in 85% of the cases. The rate of hypothyroidism resulting from these dose recommendations is the lesser evil compared to residual or recurrent hyperthyroidism, since hypothyroid patients can be treated without any problem with thyroid hormones.