Thyroid Hormones

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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. They:

  • Control the rate at which your body burns calories. 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 (located in 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.

Credits

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Matthew I. Kim, MD - Endocrinology
Specialist Medical Reviewer Andrew Swan, MD, CCFP, FCFP - Family Medicine
Last Revised February 23, 2010

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