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Women's Health

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Thyroid Hormones - Topic Overview

Thyroid hormones are made by the thyroid gland. The thyroid gland makes and releases two thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid hormones affect every cell and all the organs of the body. Too much thyroid hormone speeds things up and too little thyroid hormone slows things down. They:

  • Control the rate at which your body burns calories (your metabolism). This affects whether you gain or lose weight.
  • Can slow down or speed up your heartbeat.
  • Can raise or lower your body temperature.
  • Change how fast food moves through your digestive tract.
  • Affect muscle strength.
  • Control how quickly your body replaces dying cells.

The pituitary gland and the thyroid gland work together. The pituitary gland (located near the base of the brain) makes, stores, and releases thyroid-stimulating hormone (TSH). When TSH is secreted by the pituitary gland, it causes the thyroid gland to release more T3 and T4. A high TSH level means there isn't enough thyroid hormone, and a low TSH level means there is too much.

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By Laura NathanDoubting your diagnosis? Read on to find out what you might really have. Sometimes even the best doctors miss the mark: About 40 percent of all mistakes that M.D.s make are misdiagnoses, says the National Patient Safety Foundation. That's because many ailments have similar symptoms or can be detected only with tests that your physician might consider unnecessary if he's confident in his verdict. If you're in the know about often-confused conditions, though, you can ask the right...

Read the 4 Diseases Doctors Get Wrong article > >

    WebMD Medical Reference from Healthwise

    Last Updated: November 14, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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