The thyroid gland produces two thyroid hormones, triiodothyronine (T3) and thyroxine (T4), and releases them as needed by the body. The hypothalamus and the pituitary gland help control the thyroid gland. The hypothalamus produces thyrotropin-releasing hormone (TRH), which stimulates the pituitary gland to release thyroid-stimulating hormone (TSH). Low levels of T3 tell the hypothalamus to release more TRH and the pituitary to release more TSH. The thyroid gland releases T3 and T4 until the body is receiving the required amount.
Last Revised: July 16, 2010
Author: Healthwise Staff
Medical Review: E. Gregory Thompson, MD - Internal Medicine & Matthew I. Kim, MD - Endocrinology
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