Iodine Deficiency

Iodine is essential for thyroid hormone synthesis and is present in soil, water and air. Iodine deficiency disorders (IDD), which was referred to as endemic goiter up to thirty years ago refers to iodine deficiency that can be prevented by ensuring an adequate intake of iodine in population [64].

Goiter is the most frequent and visible manifestation of IDD and is an important health problem. It effects intellectual growth in neonates and children and almost 20 million people living in developing countries have some degree of brain damage due to the effects of iodine deficiency (ID). ID in the mother results in deficiency of the neonate. The most striking feature of ID is endemic cretinism. In severe iodine deficiency, endemic goiter and cretinism; increased perinatal death, decreased fertility rate and increased infant mortality occur. Combined iodine and selenium deficiency causes a severe form of cretinism in some areas. Two types of endemic cretinism have been defined [65-67]. In neurological cretinism, the number of neuronal cells are decreased, brain weight is reduced. Myxedematous cretinism has a less severe degree of mental retardation than neurological cretinism. Iodine deficiency in children is characteristically associated with goiter. Goiter rate increases with age and reaches a maximum at adolescence [68-70].

Iodine is present in the human body in minute amounts (10-20 |xg). The recommended dietary allowance is 60-100 |xg/daily for 1-10 years of age and 100 |xg/daily for adolescents and adults. Urinary iodine (UI) excretion provides a measure of the nutritional status of iodine in a population. Dietary iodine intake is positively correlated with its urinary excretion in iodine-repleted areas. 24-hour iodine excreted in the urine shows the iodine nutritional status, but it is impractical and can be unreliable. If nutrition is adequate UI/creatinine is considered a more reliable measure of iodine excretion than random spot UI concentration measurement since there are variations in iodine intake [71, 72]. There are several methods used to detect iodine in urine with different sensitivities; spectrophotometry method, HPLC, mass spectrometry and laser spectrometry [73-75]. UI excretion 50-99 |xg/l is defined as mild iodine deficiency,

Table 5. Prevalence of IDD in school-aged children (WHO)

Region

Africa

The Americas East Mediterranean Europe SE Asia West Pacific Total

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