Iodine

Iodine is essential for the production of thyroid hormone, and through this it has a substantial effect of metabolism and development. Iodine deficiency is also common throughout the world, with pregnant women and children at the greatest risk of being iodine deficient. Iodine deficiency is associated with adverse pregnancy outcomes including fetal loss, profound intellectual disability (cretinism), and goiter. The effects of iodine deficiency are most profound in severe deficiency, but mild to moderate iodine deficiency may have adverse consequences at the population level. Assessment of iodine status, particularly at the individual level, is challenging and further research is needed. Universal salt iodization is an effective way of correcting iodine deficiency, with periodic monitoring undertaken to prevent the consequences of iodine excess. Iodine status can also influence the frequency of thyroid autoantibodies and hypothyroidism being higher in iodine sufficient than iodine-deficient populations.