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). A low level of
T3 tells the hypothalamus to release more TRH, and it tells the pituitary to release more
TSH. The thyroid gland releases T3 and T4 until the body is receiving the
Primary Medical Reviewer
Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer
Matthew I. Kim, MD - Endocrinology
August 7, 2012
WebMD Medical Reference from Healthwise
August 07, 2012
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