What is a goiter?

Causes and Symptoms

Goiter is often a painless medical condition. Its only visible symptoms may be a slight but visible enlargement of the thyroid that creates a swelling at the base of the neck. In severe cases, the swelling becomes massive and the patient experiences difficulty breathing or swallowing as the enlarged thyroid compresses against the windpipe or esophagus. Other symptoms that may indicate goiter include weight loss, increased heart rate, elevated blood pressure, hair loss, and tremors. Goiter can be confirmed by ultrasound scan of the thyroid, blood tests for abnormal levels of thyroxine or thyroid-stimulating hormone, or low rates of iodine excretion in the urine.

The several types of medical goiter fall into two broad categories: simple goiter and toxic goiter. Simple goiter is caused by a dietary deficiency of iodine. In response, one or both lobes of the thyroid gland enlarge in an attempt to produce more of the iodine-containing hormone thyroxine. Two types of simple goiter are recognized: endemic goiter and sporadic goiter.

Endemic goiter typically occurs in landlocked geographic regions or in areas where farm soils are iodine-depleted. Simple goiter was once common in areas of central Asia, central Africa, and the so-called Goiter Belt of the United States, which extended from the Great Lakes to the Intermountain West (between the Rockies and the Sierras).

Simple goiter most often appears in adolescence, but it may sometimes occur during pregnancy. This condition should be corrected in pregnant women to ensure the healthy development of the fetus and the birth of a healthy infant. Simple goiter readily responds to treatment via iodine tablets, but in some patients surgical removal of all or part of the enlarged thyroid may be necessary. Public health measures undertaken to eliminate or prevent simple goiter include the addition of iodine to table salt and to water reservoirs in certain areas.

Sporadic goiter occurs in some individuals because of an excessive consumption of goitrogenic (goiter-causing) foods such as cabbage, soybeans, spinach, and radishes. Sporadic goiter has also been linked with exposure to certain medications, such as aminoglutethimide or lithium. Although this type of goiter is considered nontoxic, it does produce impaired thyroid activity. Sporadic goiter can be treated by limiting the consumption of goitrogenic foods.

Toxic goiter is caused by an excessive production of thyroxine hormone by the thyroid gland. This type of goiter is also called hyperthyroid goiter, exopthalmic goiter, or Graves’ disease. Toxic goiter results from an oversecretion (hypersecretion) of thyroid-stimulating hormone by the pituitary. In turn, the thyroid gland responds by enlarging and secreting excess amounts of thyroxine, resulting in goiter. Symptoms of Graves’ disease include elevated metabolic rate, higher body temperature, rapid weight loss, nervousness, and irritability. In some patients, this type of goiter results in protrusive eyeballs and the appearance of staring.

Euthyroid goiter occurs when dietary levels of iodine are only slightly below normal. The pituitary gland responds to lowered thyroxine levels in the blood by producing additional thyroid-stimulating hormone. The thyroid gland responds to the elevated thyroid-stimulating hormone by enlarging in an effort to increase thyroxine production.

Treatment and Therapy

Most goiters can be treated effectively through dietary supplements of iodine. The administration of iodine supplements must be very carefully regulated, however, to prevent a so-called thyroxin storm resulting from excess thyroxine production by the enlarged thyroid gland. Some patients may choose alternative natural herbal therapies taken in tablet form, but these substances should be used only in consultation with a physician.

Bibliography:

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Gaitan, Eduardo, ed. Environmental Goitrogenesis. Boca Raton, Fla.: CRC, 1989.

Hall, R., and J. Köbberling, eds. Thyroid Disorders Associated with Iodine Deficiency and Excess. New York: Raven Press, 1985.

Hamburger, J. I. Nontoxic Goiter: Concept and Controversy. Springfield, Ill.: Charles C. Thomas, 1973.

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