Labels:text | screenshot | black and white | black | font | document OCR: ctive The thyroid gland produces two major thyroid hormones, thyroxine (T4) and these triiodothyronine (T3). The production o Iby hormones within the thyroid is regulate one; TSH), thyrotrophin (thyroid-stimulating horn uitary (Fig.a glycoprotein secreted by the anterior p of TSH are 15.1). In turn, the production and release mone controlled by thyrotrophin-releasing ho sed from (TRH), a tripeptide synthesised and rele es are also the hypothalamus. Higher cerebral cent on. known to influence hypothalamic func gative Circulating levels of T4 and T3 exert a n pituitary feedback effect on TSH secretion via the h levels of and also the hypothalamus, whereby hi T4 or T3 T4 or T3 suppress TSH, and low levels o stimulate TSH secretion. See later: . Basal TSH Examination · TSH/TRH Test.