The Role of Iodine Deficiency and Subsequent Repletion in Autoimmune Thyroid Disease and Thyroid Cancer
Iodine is an essential trace mineral that is necessary for thyroid hormone production. With the prevalence of iodine deficiency worldwide, universal salt iodization programs were successfully implemented to reduce the incidence of iodine deficiency disorders; however, unexpected increases in the prevalence of thyroid autoimmunity occurred, and iodine excess was implicated as the causative factor. Despite these observations, epidemiological studies are inconsistent, and the etiology of autoimmune thyroid disease remains undefined. A review of observational and in vitro studies revealed that iodine alone is not responsible for thyroid autoimmunity.