Hormone, thyroid stimulating (TSH): A hormone produced by the pituitary gland at the base of the brain in response to signals from the hypothalamus gland in the brain.
TSH promotes the growth of the thyroid gland in the neck and stimulates it to produce more thyroid hormones. When there is an excessive amount of thyroid hormones, the pituitary gland stops producing TSH, reducing thyroid hormone production. This mechanism maintains a relatively constant level of thyroid hormones circulating in the blood.
Thyroid stimulating hormone is also known as thyrotropin.