Supplement: Iodine and Autoimmune Thyroid Diseases

A number of clinical and epidemiological studies suggest that the incidence of autoimmune thyroid diseases (AITDs), such as Hashimoto thyroiditis and Graves disease, goes up as dietary iodine increases. Even though iodine is necessary for proper thyroid function, some people who are genetically predisposed to an AITD may be getting too much.

This could be related to the iodination of thyroglobulin, the source protein of the thyroid hormones. Yaron Tomer, a professor of medicine at the University of Cincinnati, found that certain amino acid variants of the thyroglobulin gene predispose individuals to thyroid autoimmunity (Y. Ban et al., "Genetic susceptibility in thyroid autoimmunity," Pediatr Endocrinol Rev, 3:20-32, 2005). But, says Tomer, "We did not test yet whether these sequence variants influence the iodination...