E. Molitch, M.D.Northwestern University Medical School
Pituitary Hormones and Their Regulation
Hypopituitarism refers to the condition in which one or more of the 6 pituitary hormones are deficient. Growth hormone (GH, also known as somatotropin) is the hormone primarily responsible for growth in children but it may also play a role in adults in regulating fat and muscle tone. Prolactin (PRL) is the hormone primarily responsible for breast milk production after delivery in women; its roles outside of this function in women and in men are unknown. Adrenocorticotropic hormone (ACTH) is that hormone necessary to stimulate the adrenal gland to produce its hormones, cortisol and adrenal androgens, especially in times of stress. Thyroid stimulating hormone (TSH or thyrotropin) is that hormone necessary to stimulate the thyroid hormone to produce its hormones, thyroxine (T4) and triiodothyronine (T3). Finally, the hormones luteinizing hormone (LH) and follicle stimulating hormone (FSH) together are responsible for the maturation of eggs and the secretion of estrogens by the ovary and for the maturation of sperm and the secretion of testosterone by the testes. Thus, these hormones have different functions and the loss of one or more will cause different types of symptoms and conditions.Each of these pituitary hormones is regulated by other hormones which come from a portion of the brain called the hypothalamus. These hormones are made by nerve cells within the hypothalamus and they are released into blood vessels at the bottom of the hypothalamus. The blood vessels traverse the stalk that connects the hypothalamus to the pituitary and the bottom end of the blood vessels end on the cells in the pituitary that make the pituitary hormones. Most of these hypothalamic hormones stimulate the release of the pituitary hormones but others block the release of the pituitary hormones.
