Topic updated: June 2012

Thyroid Gland Disorders

The thyroid is a small butterfly-shaped gland inside the neck, located in front of the breathing airway, or trachea, and below the larynx, or voicebox. It produces two thyroid hormones - tri-iodothyronine (T3) and thyroxine (T4) - that travel though the blood to all tissues of the body.

Thyroid hormones regulate how the body breaks down food and either uses that energy immediately or stores it for the future. In other words, our thyroid hormones regulate our body's metabolism.

Another gland, called the pituitary gland, actually controls how well the thyroid works. The pituitary gland is located at the base of the brain and produces thyroid-stimulating hormone. The bloodstream carries this thyroid-stimulating hormone to the thyroid gland, where it tells the thyroid to produce more thyroid hormones, as needed.

Thyroid hormones influence virtually every organ system in the body. They tell organs how fast or slow they should work. Thyroid hormones also regulate the consumption of oxygen and the production of heat.

Endocrinologists - physicians and scientists who study and care for patients with endocrine gland and hormone problems - study and treat several major disorders of the thyroid gland. We will briefly describe these disorders and some thyroid disease symptoms here.

Hyperthyroidism

Too much thyroid hormone from an overactive thyroid gland is called hyperthyroidism, because it speeds up the body's metabolism. This hormone imbalance occurs in about 1 percent of all women, who get hyperthyroidism more often than men. One of the most common forms of hyperthyroidism is known as Graves' disease. This autoimmune disorder tends to run in families, although the exact nature of the genetic abnormality is unknown.

Because the thyroid gland is producing too much hormone in hyperthyroidism, the body develops an increased metabolic state, with many body systems developing abnormal function. 

Hypothyroidism

Too little thyroid hormone from an underactive thyroid gland is called hypothyroidism. In hypothyroidism, the body's metabolism is slowed. Several causes for this condition exist, most of which affect the thyroid gland directly, impairing its ability to make enough hormone. More rarely, there may be a pituitary gland tumor, which blocks the pituitary from producing TSH. As a consequence, the thyroid fails to produce a sufficient supply of hormones needed for good health.

Whether the problem is caused by the thyroid conditions or y the pituitary gland, the result is that the thyroid is underproducing hormones, causing many physical and mental processes to become sluggish. The body consumes less oxygen and produces less body heat.

Thyroid Nodules

A thyroid nodule is a small swelling or lump in the thyroid gland. Thyroid nodules are common. These nodules represent either a growth of thyroid tissue or a fluid-filled cyst, which forms a lump in the thyroid gland. Almost half of the population will have tiny thyroid nodules at some point in their lives but, typically, these are not noticeable until they become large and affect normal thyroid size. About 5 percent of people develop significant sized nodules, greater than a half inch across (about 1 centimeter).

Although most nodules are not cancerous, people who have them should seek medical attention to rule out cancer. Also, some thyroid nodules may produce too much thyroid hormone or become too large, interfering with an individual's breathing or swallowing or causing neck discomfort.

Other problems

Other thyroid problems include cancer, thyroiditis (swelling of the thyroid gland), or a goiter, which is an enlargement of the thyroid gland.

Read more articles about thyroid disorders from the Hormone Foundation.

Thyroid image reproduced with permission from Philip Wilson, Medical & Scientific Illustrator in Orpington, Kent, England. All rights reserved. For more information see their website at: www.medart.co.uk

Illustration of thyroid

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