[Iodine and thyroid autoimmunity]

The pathogenetic mechanisms leading to the development of autoimmune disease of the thyroid are based on several different factors. The resultant immune response is related to both the genetic predisposition and other influencing factors such as iodine intake, a very important modulator of thyroid autoimmunity. To a large extent, the details of the mechanisms that induce the immune response and lead to chronic autoimmune thyroid reactions are still poorly understood. In genetically predisposed individuals the iodine intake modulates autoimmune thyroid reactions. Especially with acute or chronic increase of iodine intake it leads to a significant increase in the incidence and intensity of autoimmune thyroid disease. There is a need to further investigate whether the results of experimental animal studies can be generalised to humans. Epidemiological data from countries with sufficient or high nutritional iodine intake clearly show that in comparison to countries with iodine deficiency there is an increase in the incidence of autoimmune thyroid disease and a change in the pattern of manifestation, e.g. in the proportion of autoimmune thyroiditis and hyperthyroidism due to Graves' disease. At the same time, thyroid diseases related to iodine deficiency significantly decrease, which is to be expected with a continuously higher iodine intake.