Thyroid stimulating hormone (TSH) or thyrotropin of the anterior pituitary gland enhances synthesis & secretion of thyroid hormones by the thyroid gland.
Production of TSH by the pituitary is controlled by a stimulatory effect of thyrotropin-releasing hormone (TRH) of the hypothalamus by feedback from circulating free T3 & free T4. Accordingly, the hypothalamus (via TRH), sets the level of thyroid hormones production required physiologically by the body.
