There are different kinds of goiters. A simple goiter usually occurs when the thyroid gland is not able to produce enough thyroid hormone to meet the body's needs. The thyroid gland makes up for this lack by enlarging, which usually overcomes mild deficiencies of thyroid hormone. A simple goiter may be classified as either an endemic (colloid) goiter or a sporadic (nontoxic) goiter. Endemic goiters occur within groups of people living in geographical areas with iodine-depleted soil, usually regions away from the sea coast. People in these communities might not get enough iodine in their diet (iodine is vital to the formation of thyroid hormone). The modern use of iodized table salt in the U.S. prevents this deficiency. However, inadequate iodine is still common in central Asia and central Africa. In most cases of sporadic goiter the cause is unknown. Occasionally, certain medications such as lithium or aminoglutethimide can cause a nontoxic goiter. Hereditary factors may cause goiters. Risk factors for the development of a goiter include female sex, age over 40 years, inadequate dietary intake of iodine, residence in an endemic area, and a family history of goiter.
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