Endocrine Abstracts

Abstract: Radioiodine is a definite treatment option for toxic goiter. We have evaluated volume reduction, function and autoimmunity outcomes with a 15 mCi fixed regimen. Patients with at least one US evaluation before and after Iodine-131 therapy and with at least one year of follow-up were included. TSH, free-T4, antibodies and goiter volume before and yearly after Iodine-131 treatment were analysed for the length of the entire follow-up. The total 151 patients, 72.6% females, had a mean follow-up of 6.2 (1–12) years. At the time of treatment, the mean age was 68.8 years and the initial goiter volume 48.9 (8–255.7) ml, with no statistical difference between sexes. Increased volume was observed in 96.5% females and 91.7% males and there were 10.6% in hyperthyroidism and 89.4% in subclinical hyperthyroidism. The mean percentage volume reduction in the first year was 29.8% which represents 14.7 ml with a Pearson coefficient of correlation with initial volume of 0.058. During the following years mean reductions of 19.7, 15.8, 9.7, 5.8 and 1.4% were observed. Absolute volume reductions were maximal at the 3rd and 4th years representing mean reductions of 50 and 52%. Initial volume, TSH and age could not produce an explicative model for the percentage of reduced volume. Euthyroidism was achieved in 60.9% patients, subclinical hyperthyroidism in 8.6% and hypothyroidism in 26.5% of which 23.8% were subclinical. Hypothyroidism was related significantly with initial volume (P<0.001) and maximal percentage of reduction (P=0.012). The development of new detectable anti-thyroid antibodies was identified in 5 patients (6.9%), the result being above cut-off in none of them. New anti-TSH-receptor antibodies developed in 4 (5.5%) patients 1–3 years post-treatment. With 15 mCi, all patients experienced volume reduction in the first years after treatment, achieving means above 50% at the 3rd year, most were rendered euthyroid and developed no auto-immunity.