Thyroid hormones

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.



Author: Alison Allen
Caroline Rea, RN, BS, MS
Last Updated: February 12, 2008
Medical Review: Anne C. Poinier, MD - Internal Medicine
Caroline S. Rhoads, MD - Internal Medicine
David C.W. Lau, MD, PhD, FRCPC - Endocrinology & Metabolism

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