GOITER

Goiter
Goiter, disease of the thyroid gland, characterized by an enlargement of the gland, visible externally as a swelling on the front of the neck. In simple goiter the basal metabolic rate is somewhat lowered, and in toxic goiter it is elevated.

Simple Goiter
Simple goiter is characterized by an enlargement of the entire thyroid gland or one of its two lobes. It is associated with hypothyroidism, a condition caused by insufficient production of thyroid hormone. Because the body needs iodine to produce thyroid hormone, inadequate amounts of iodine in the diet may result in simple goiters. Simple goiters may be classified as either endemic or nontoxic.
Endemic goiters are caused by a deficiency of iodine in the diet and usually occur in populations living in areas with iodine-depleted soil. It once was common in what was referred to as the goiter belt of the United States, largely the Midwestern states. Public health measures, including the addition of iodine to water supplies and to table salt, have helped the prevention of endemic goiters in the United States. Ingestion of iodine supplements during pregnancy prevents development of the disease in the infant as well as in the mother.
The cause of most nontoxic goiters is unknown, but researchers suspect that environmental factors and heredity play a role. In some areas of the world, certain chemical compounds in food or water may block the body’s production of thyroid hormones and lead to nontoxic goiter formation. These compounds, known as goitrogens, also include certain drugs, such as aminoglutethimide and lithium.
Most simple goiters do not produce symptoms. The administration of thyroid hormone will lead to a reduction in size of simple goiters in most cases. Surgical removal of a simple goiter is usually unnecessary unless the goiter is very large and is impingeing on vital body organs.
Toxic goiter
This disease, also called exophthalmic goiter, hyperthyroidism, thyrotoxicosis, or Graves' disease, for the Irish physician Robert James Graves, is caused by an excess of thyroxine secretion. The cause of the excessive secretion is obscure. In some cases it may result from excessive stimulation by the pituitary gland. The symptoms of toxic goiter may include a rapid heartbeat, tremor, increased sweating, increased appetite, weight loss, weakness, and fatigue. Some patients have eye problems, such as staring or protrusion. Toxic goiter is commonly treated with radioactive iodine, which is taken up by the gland and destroys the cells by irradiation. Drugs also can be used to suppress hormone production, or most of the toxic goiter can be removed surgically.