Thyroid-stimulating hormone (TSH or thyrotropin), produced in human pituitary glands, has a molecular mass of 25kD. An Important indicator of thyroid function, TSH is used to monitor thyroid associated diseases. Thyroid-stimulating hormone is a hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland. TSH stimulates the thyroid gland to secrete the hormones thyroxine (T4) and triiodothyronine (T3). TSH production is controlled by a Thyrotropin Releasing Hormone (TRH), which is manufactured in the hypothalamus and transported to the anterior pituitary gland, where it increases TSH production and release. Somatostatin is also produced by the hypothalamus, and has an opposite effect on the pituitary production of TSH, decreasing or inhibiting its release.