Definition of Goiter - simple:

A goiter is an enlargement of the thyroid gland. It is not cancer.

See also:

• Colloid nodule goiter
• Toxic nodule goiter

Causes, incidence, and risk factors:

There are different kinds of goiters. A simple goiter can occur for no known reason, or 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 by becoming larger.

There are two types of simple goiter:

• Endemic (colloid) goiter
• Sporadic (nontoxic) goiter

Colloid goiters occur in groups of people who live in areas with iodine-poor soil. These regions are usually away from the sea coast. People in these communities might not get enough iodine in their diet (iodine is needed to produce thyroid hormone).

The use of iodized table salt in the United States today prevents iodine deficiency. However, the Great Lakes, Midwest, and inner mountain areas of the United States were once called the "goiter belt," because a high number of goiter cases occurred there. A lack of enough iodine is still common in central Asia, the Andes region of South America, 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.

Inherited factors may cause goiters. Risk factors include:

• Age over 40 years
• Family history of goiter
• Female gender
• Not getting enough iodine in the diet