[Disorders associated to chronic iodine deficiency]

The thyroid gland promotes its adaptation to iodine deficiency inducing an increase in the iodine uptake followed by a substantial increase in the thyroid gland mass (goiter). Simultaneously, there is a preferential T3 secretion by the follicular cell and a persistently elevated serum TSH. Laboratory tests, isotopic methods and imaging are routinely used to verify the altered thyroid pathophysiology. In certain populations the presence of goitrogenic natural substances, present in the locally consumed staple food, were found and may add to the pathogenic process. Endemic cretinism is usually present when the iodine deficiency is quite low and may present with the neurologic or myxedematous sub-types, frequently associated with deafmutism. In Brazil, the prevalence of iodine-deficiency disorders has been evaluated, periodically, with schoolchildren examined for goiter. Universal salt iodination was implemented in Brazil in the early fifties but recently the system was considered effective for the supply of iodine to the Brazilian population.