Abstract: Iodine is a key element in the synthesis of thyroid hormones and maintaining the normal physiological function. The iodine excess can lead to hypothyroidism, hyperthyroidism and autoimmune thyroid diseases. Individuals have different susceptibility to iodine excess. Excessive oxidative stress and secondary immune response may be the potential mechanisms of thyrotoxicity induced by iodine excess. This review updates the epidemiological results of iodine excess, and recommended intake standards, which may be involved in iodine excess and the regulatory mechanisms and pathogenesis in body to counteract iodine excess.

Key words: iodine, thyroxine, thyrotropin, iodine excess, epidemiology, reference values, pathogenic mechanism, oxidative stress, immune reaction