TREATMENT OF GRAVES HYPERTHYROIDISM WITH RADIOIODINE - RESULTS OF A PROSPECTIVE RANDOMIZED STUDY

In this paper, we report the results of a randomized prospective study on radioiodine treatment in patients with Graves' hyperthyroidism. Co mplete data were obtained in group 1 from 98 patients 6 months after a pplication of a standard activity of 15 mCi (555 MBq) of I-131 and in group 2 from 107 patients who received a target dose of 100 Gy. In gro up 1, the overall success rate was 71%, but the results in the subgrou ps clearly were related inversely to the thyroid volume, ranging from 100%, in patients with a thyroid volume <15 mL to about 20% in those w ith a thyroid size >60 mL. In contrast, patients who received a target dose of 100 Gy showed very similar results, with success rates of abo ut 40-50% in all but one subgroup. Only patients with a thyroid volume <15 mL had a success rate of about 80%. But due to an incidental incr ease of uptake and/or effective half-time from the test to the therapy activity, this subgroup received a target dose of about 160 Gy. Addit ional calculation of the actual target dose in group 1 (standard activ ity) showed that, with a dose of 200 Gy, a success rate of 80% was obt ained. Also, the thyroid volume reduction was related inversely to the target dose. Because the literature is abundant, only a restricted nu mber of references are discussed that are either in agreement with our results or in sharp contrast to them. The reason for these discrepant results might be the difference in the scheme of pretreatment or the different alimentary iodine supply between, for example, Great Britain and the United States on the one hand and Germany on the other hand.