Endocrine Abstracts

Introduction: Effects of selected drugs on the efficacy of (¹³¹I) radioiodine therapy were examined.

Material and methods: The study involved 200 hyperthyroid patients, treated with radioactive iodine. They were divided into five (5) groups (40 persons in each). In group I – beside ¹³¹I, patients were additionally administered antithyroid drugs, in group II – ¹³¹I and lithium carbonate, group III – ¹³¹I only (the assumed absorbed dose – 150–200 Gy, the same as in groups I and II, controls), in group IV – ¹³¹I and corticosteroids and in group V – ¹³¹I only (250–350 Gy, the same as in group IV, controls). Therapeutic results were evaluated after 6 months on the basis of clinical and hormonal status. The evaluation included also effects of the initial hormonal status on the outcome of ¹³¹I therapy in groups II and IV (versus respective controls, groups III and V); such an analysis was not performed in group I because all the patients in that group were initially hyperthyroid. The results of treatment were assigned into 2 classes in each of the study groups: effective therapy – euthyroidism or hypothyroidism; ineffective therapy – persistent hyperthyroidism.

Results: In 145 patients (72.5%), the therapy with ¹³¹I was effective (group I – 55.0%, group II – 72.5%, group III – 75.5%, group IV – 87.5%, group V – 70.0%). In 55 patients (27.5%), the therapy with ¹³¹I turned out ineffective.

Conclusions: The application of thiamazole during peritherapeutic period in patients, treated with ¹³¹I, reduced the effectiveness of radioiodine, while lithium carbonate had no effect on the therapy outcome. Prednisone increased the effectiveness of the therapy with radioiodine. Normalisation of the initial concentration of TSH was favourable for the ¹³¹I therapeutic outcome only when the assumed absorbed doses of 150–200 Gy were applied.