Iodine

Iodine is an essential substrate for synthesis of thyroid hormones. When the physiological requirements of iodine are not met in a given population, a series of functional and developmental abnormalities occur and, when iodine deficiency is severe, endemic goitre and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death and infant mortality. Endemic cretinism knows a neurological and a myxoedematous form, with mixed forms. In affected populations one finds mental retardation, deafmutism, spastic diplegia, squint, hypothyroidism and dwarfism (Delange 1994). Although the best known clinical sign of iodine deficiency is goitre, this does not represent the mayor health problem. Iodine deficiency during pregnancy is responsible for development defects of the foetus and the pathologies associated with endemic goitre. Iodine supplementation studies have shown beyond doubt that supplementing iodine during pregnancy can reverse the described abnormalities (Pharoah 1993). Maternal health seems not directly affected by iodine deficiency. Salt fortification is now widely practised throughout the world with an impressive decrease in associated morbidity (Delange 1998).