Hypothyroidism

Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormone. It is the most common thyroid disorder, far more common than hyperthyroidism (an overactive thyroid). It is estimated that about 10% of women and 3% of men have hypothyroidism.

If you have too little thyroid hormone-even after your pituitary has signaled your thyroid gland to turn up the production and make more, then your metabolism is slower than normal. If your TSH level is higher than normal, and your thyroid hormone levels are lower than normal, it confirms that your body is attempting to step up the production and release of thyroid hormone because you don't have enough.

What happens when you don't have enough thyroid hormone is that your whole body slows down. You may feel tired and cold, have a slow heartbeat, gain weight unexpectedly, and/or feel depressed. In fact, too little thyroid hormone can affect nearly every part of your body.

Left untreated, hypothyroidism can produce serious health problems.

In about 95 percent of cases, hypothyroidism is due to a problem in the thyroid gland itself and is called PRIMARY HYPOTHYROIDISM. Certain medications and diseases can decrease thyroid function, and, ironically, hypothyroidism can also follow medical treatments for hyperthyroidism, such as thyroidectomy (surgical removal of the thyroid) or radioactive iodine treatment (to destroy thyroid tissue). In some cases, hypothyroidism is a result of decreased production of TSH and is called SECONDARY HYPOTHYROIDISM.

In the beginning stages of hypothyroidism, the symptoms can be mild, and go undetected. Sometimes, hypothyroidism is not diagnosed until symptoms have been present for a long time. However, simple blood tests can now detect hypothyroidism at an early stage. The umbilical cord blood of all newborn babies is tested for TSH.

A more mild form of hypothyroidism is mild thyroid failure. In this case, your thyroid hormone levels are normal, but you have a high TSH level. This may mean that TSH is making your thyroid gland work extra hard just to maintain normal levels of hormone in your blood. This condition often leads to hypothyroidism. People with mild thyroid failure generally don't show any obvious symptoms, which makes it very difficult for doctors to identify without performing a TSH test.

The symptoms of hypothyroidism vary widely, from no symptoms to marked symptoms to, rarely, life-threatening symptoms. The symptoms of hypothyroidism are notorious for their nonspecific nature and for the way in which they mimic many of the normal changes of aging. The extent of symptoms depends on the severity of the hormone deficiency and the speed with which the deficiency developed. Usually, symptoms are milder when the hypothyroidism has developed gradually.