Iodine Deficiency and Thyroid Function

Iodine deficiency still represents a global health threat to individuals and societies. Although goiter is the most frequent consequence of an inadequate iodine intake, iodine deficiency has multiple adverse effects on growth and development in animals and humans. These are collectively termed iodine deficiency disorders (IDD) and result from inadequate thyroid hormone production due to insufficient iodine intake. Iodine deficiency during pregnancy and breast feeding adversely affects the neurodevelopment of the fetus and the infant. During childhood, it has been linked to reduced growth and intellectual and motor performance. Goiter in children is usually small and diffuse, but over time may evolve toward nodular goiter. Adults living in iodine-deficient regions show a high risk of goiter, thyroid nodules, and hyperthyroidism. To eradicate IDD, the WHO recommended universal salt iodization as the preferred strategy. Over the years, voluntary or mandatory programs of salt iodization have been implemented in many countries. The WHO recommends combining strategies of salt/sodium reduction with parallel salt iodization programs. To make both prevention programs effective, iodine prophylaxis programs should be adapted to the actual salt intake of the population by increasing iodine concentration of iodized salt, when necessary, and by promoting the use of iodized salt in processed food production.