Iodine deficiency disorders

Iodine deficiency is a major public health problem for populations throughout the world, particularly for pregnant women and young children. They are a threat to the social and economic development of countries. Goitre is the most visible manifestation of IDD. Endemic goitre results from increased thyroid stimulation by thyroid stimulating hormone (TSH) to maximize the utilization of available iodine and thus represents maladaption to iodine deficiency . However, the most damaging disorders induced by iodine deficiency are irreversible mental retardation and cretinism . If iodine deficiency occurs during the most critical period of brain development (from the fetal stage up to the third month after birth), the resulting thyroid failure will lead to irreversible alterations in brain function. In severely endemic areas, cretinism may affect up to 5–15% of the population. While cretinism is the most extreme manifestation, of considerably greater significance are the more subtle degrees of mental impairment leading to poor school performance, reduced intellectual ability and impaired work capacity. Introduction Iodine deficiency is a major public health problem for populations throughout the world, particularly for pregnant women and young children. They are a threat to the social and economic development of countries (1). The geographical distribution of severe endemic areas has been progressively reduced, and at present, approximately 200 million people living in remote places are still at risk of severe iodine deficiency (2). Functions Iodine is stored in the thyroid gland, where it is used in the synthesis of triiodothyronine (T4) and thyroxine (T3). Thyroid hormone is degraded in target cells and the liver, and the iodine is highly conserved under normal conditions. Selenium is important in iodine metabolism because of its presence in one enzyme responsible for forming active T3 from thyroglobulin Stored in the thyroid gland. Dietary Reference Intakes An iodine intake of 150 g/day has been suggested as sufficient for all adults and adolescents. The RDA for pregnant and lactating women increases to 220 microgram and 290 microgram ,respectively.The RDA is 110 g for infants up to 6 months of age and 130 g for older infants.The RDA for children is between 90 and 120g and increase with age (or body size)(3). Food Sources and intakes Iodine and iodine-rich foods have long been used as a treatment for hypertension and cardiovascular disease (4).The native iodine content of most foods and beverages is low, and most commonly consumed foods provide 3 to 80 g per serving. Iodine content in foods is also influenced by iodine-containing compounds used in irrigation, fertilizers, and livestock