The disorders induced by iodine deficiency affect at least one billion people. Because ofits effects on brain development, iodinedeficiency is the single most preventable cause of mental retardation in the world. Therefore, the United Nations and the Heads of State of almost all the world's countries represented at the Summit for Children in 1990 adopted resolutions to eradicate the disorders induced by iodine deficiency (IDD) by the year 2000. For geological and socio-economic reasons, most of the populations affected by iodine deficiency disorders live in isolated and usually mountainous...

Systematic screening for congenital hypothyroidism in the newborn was introduced some 15 years ago. The main objective was the prevention of mental retardation due to thyroid hormone deficiency during the early months of life. During the past decade screening programs have become routine throughout most of the industrialized world and many questions relating to implementation, organization and quality control of such programs have been largely resolved. Preliminary IQ and neurological data have indicated that screening and early treatment do, in fact, prevent mental retardation. However, a...