What Is Hypothyroidism?

Hyperthyroidism is the decreased production of thyroid hormone by the body, sometimes stemming from an auto-immune disorder. It is treated with relative ease with hormone supplements.

The thyroid gland is responsible for the production of thyroid hormone, one of several substances responsible for the regulation of the body's metabolism. Hypothyroidism is a condition in which the thyroid gland does not produce sufficient amounts of thyroid hormone, for one of various reasons, which can affect many of the body's organs and processes.

The most common worldwide cause of hypothyroidism is a nutritional deficiency of iodine. This is not a concern in most industrialized nations, who have adopted the addition of iodine to foods, namely salt.

In the United States and other industrialized nations, hypothyroidism is less common, and is more often the result of an auto-immune disorder known as Hashimoto's thyroiditis, clinically, chronic autoimmune thyroiditis. Like a similar condition, Graves-Basedow disease, Hashimoto's thyroiditis is the result of the body's production of antibodies which attack the thyroid gland, mistaking its cells for foreign bodies. Whereas Graves-Basedow disease results in the inflammation and resulting hyperactivity of the gland, Hashimoto's thyroiditis results in damage to the gland that leads to the under-production of thyroid hormone. Often, Graves' disease can lead, with time, to Hashimoto's thyroiditis. Auto-immune disorders are relatively uncommon, but account for many of the body's hormonal disorders, including diabetes, with which chronic autoimmune thyroiditis is sometimes associated. Hashimoto's thyroiditis most commonly affects women and the elderly.


Hypothyroidism may also result from radioactive iodine therapy or surgery meant to treat hyperthyroidism, which may include the partial or complete removal of the thyroid gland or benign nodules that have grown upon it.

An underproduction of thyroid hormone tends to result in lowered metabolism, often resulting in severe fatigue, depression, and the inability to stay warm, among other symptoms. Potentially severe constipation is a common side-effect, as the slower the body processes food the more moisture it will draw from the waste. Weight gain is also associated with hypothyroidism.

A condition referred to as "mild", or subclinical, hypothyroidism may also occur, the result of only slightly depressed blood levels of thyroid-stimulating hormone and/or thyroid hormone. Symptoms for individuals with subclinical hypothyroidism may be non-apparent or very mild, but those with the condition are at increased risk for the full form of the condition later in life. Those identified with subclinical hypothyroidism will usually be checked for the presence of antithyroid antibodies in the blood, which, if present, may indicate the coming onset of Hashimoto's thyroiditis. If these antibodies are present, it is likely that the thyroid gland's activity has only thus far been marginally impaired. Treatment for subclinical cases is not always viable or necessary.

A physical exam and blood test are the usual methods by which hypothyroidism is identified. The blood is checked for levels of thyroid-stimulating hormone and thyroxine, which, if low, may indicate the presence of the condition.

Synthetic hormones are the most effective treatment for hypothyroidism, and may frequently resolve all symptoms. Depending upon the cause of the condition, such supplements may be taken for one's entire life. Some cases of hypothyroidism, such as that caused by infection, will usually return to normal on their own, but may be treated with hormone supplements in the short term.

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