URINARY IODINE CONCENTRATION IS INVERSELY ASSOCIATED WITH THE THYROGLOBULIN ANTIBODY.

OBJECTIVE: Epidemiologic studies on the relationship between iodine and thyroid antibodies were inconsistent. Iodine nutrition, genetic and environmental factors have been shown to modify the effects of iodine on thyroid autoimmunity. We investigated the relationship between urinary iodine concentration (UIC) and thyroglobulin antibodies (TgAb) in individuals living in iodine sufficient areas in this cross-sectional study.

METHODS: A total of 15008 participants were recruited according to the age range of China population in our study. An oral questionnaire was administrated to collect basic demographic information. Serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), TgAb, and UIC were measured and thyroid ultrasonography was performed in all subjects. Participants were further divided according to the level of UIC and the status of TgAb, and logistic regression was applied to determine the relationship between UIC and TgAb.

RESULTS: The median UIC of the study population was 205.23(65.7-537.67) μg/L. 17.6% participants had UIC<100μg/L. With the increase in UIC, the prevalence of positive TgAb decreased gradually. UIC level was lowest in high titers of TgAb group [182.36 (52.88-506.71) μg/L] and highest in the negative TgAb group [207.16 (66.94-538.72) μg/L]. Multilinear correlation analysis showed that gender (β=37.632, p<0.001), age (β=0.467, p=0.038), TSH (β=13.107, p<0.001), TPOAb (β=1.150, p<0.001), thyroid volume (β=2.883, p<0.001) and UIC (β=-0.047, p=0.032) were independent predictors of TgAb variations. Low UIC (UIC<100 μg/L) was associated with the increased risk of positive TgAb (adjusted odds ratio=1.255[1.004-1.568]).

CONCLUSIONS: Low urinary Iodine concentration was an independent risk factor for positive TgAb for individuals living in iodine sufficient areas.