[A five-year follow-up of two different 131I treatment methods for Graves' disease and the factors affecting the outcome].

We employed two different methods of 131I treatment for Graves' disease in 285 patients and compared the results between the two. (We also analyzed the factors affecting the treatment outcome.) A single dose of 131I adjusted to the patients' thyroid weight was administered to 180 patients in group 1, while a relatively lower dose of 131I (approximately 30Gy) was given repeatedly to 105 patients in group 2. A 5-year follow-up showed that in group 1, 34% of the patients were euthyroid, 11% hypothyroid, 11% subclinical hypothyroid and 44% still remained hyperthyroid. In group 2, 43% of the patients were euthyroid, 5% hypothyroid, 35% subclinical hypothyroid and 17% hyperthyroid. The factors affecting the outcome of the treatment in group 1 patients were their thyroid weight, the duration of the disease and TRAb levels. No significant correlation was observed between the efficacy of 131I treatment and the patients' sex, age, 24hr 131I-uptake, effective half life of administered 131I or titers of antithyroid antibodies. We conclude that the repeated low dose administration of 131I provides the best outcome in a 5-year follow-up. However, we suggest that an adjusted dose of 131I in relation to the patients' thyroid weight should be employed to obtain a faster therapeutic response.