FRI534 Influence Of Radioiodine Therapy Of Huge Thyroid Goiter On The Development Of Autoimmune Thyroid Disease In Retreated Patents

Disclosure: A. Skoczylas: None. A. Kluza: None. E.C. Lubocka: None. W. Mularczyk: None. M. Zyla: None. K. Fortuna: None. I. Linkert: None. J. Raniszewska: None. M. Skoczylas: None. P. Piwkowski: None. A. Golebiowska: None. A. Partyka: None. P. Wozniak: None. D. Jedrzejuk: None. The aim of this study was to estimate the levels of thryoid antibodies: aTPO, aTG and TRAb in basic conditions and after subsequent radioactive iodine (I-131) administrations in patients with huge nodular goiter and to assess whether subsequent doses of I-131 alter these levels. Methods 260 patients 199F/61M aged 41-88 years with mean TSH concentration of 1.0 and nodular goiter of mean weight 93g (35-364g) assessed on iodine scintigraphy, with contraindications to surgical treatment were enrolled to this study. These patients were qualified for I-131 cytoreduction. The activity planned for treatment was divided into fractionated doses of 0.8 GBq, which were given at 3-month intervals up to 4 times. Before each treatment, as well as 3 months after the last one, immunological and biochemical tests were performed. Elevated levels of aTPO and aTG were confirmed in 33 qualified patients. Statistics The statistical significance of differences in antibody concentrations between rounds was measured using the Skillings-Mack nonparametric test (SM-t). Dunn-Bonferroni post hoc method (DB) was used to assess the significance of pairwise differences in antibody levels between studies. Correlations between changes in antibody levels and goiter parameters were studied using the Spearman's Rank correlation - a value of p<0.05 was taken as significant. Results The SM-t showed that there was a statistical difference in TRAb resulting from the I-131 administration SM-t=42.35, p<0.001. DB test showed a significant increase in TRAb levels compared to baseline Me=0.30 from the second I-131 administration Me=0.35, p<0.01, but exceeded the upper normal range in only 6 patients. The first treatment did not change TRAb levels Me=0.30, p>0.05 significantly. The SM-t showed a statistical difference in aTG levels SM-t=38.74, p<0.01. DB analysis showed that compared to the baseline Me=11.60, the level had already changed significantly from the first administration of I-131 Me=13.50, p<0.01, and retreatments no longer changed the concentration of aTG significantly. Retreatments resulted in significant differences in aTPO SM-t=16.08, p<0.01, but DB test did not specifically indicates between which I-131 administrations these differences were significant. In the group with baseline immune abnormalities, statistical analysis indicated the existence of differences in TRAb SM-t=1.63, p<0.05 and aTPO SM-t=17.72, p<0.05 levels, but no significant correlation was observed between changes in the level of tested antibodies and changes in descriptive goiter parameters. Conclusion Initial I-131 therapy did not change the TRAb concentration, but subsequent treatments led to a significant increase in TRAb concentrations compared to baseline measurements. The concentration of aTG significantly increased immediately after the first I-131 therapy but subsequent treatments no longer changed their concentration Presentation: Friday, June 16, 2023