The Pituitary Tumor Center at Johns Hopkins

The pituitary gland is a pea-size gland located behind our eyes and often considered the “master endocrine gland.” It regulates most of the body’s hormonal balance. In particular, it controls the function of the adrenal glands, the thyroid, and the ovaries or testes. In addition, it produces growth hormone (GH) which is necessary for growth during childhood and prolactin which is necessary for milk production after pregnancy and delivery.

The pituitary has two parts. The anterior lobe is the source of prolactin, GH, thyroid-stimulating hormone (TSH, controlling the thyroid), gonadotropic hormones (LH and FSH, controlling testes or ovaries) and adrenocorticotropic hormone (ACTH, controlling the adrenal glands). The posterior lobe contains nerve fibers coming from the brain (hypothalamus) storing oxytocin (necessary for uterine contractions during delivery) and anti-diuretic hormone (necessary to regulate the amount of urine we make).

The most frequent cause of pituitary malfunction is a benign tumor (adenoma) of the gland. Pituitary failure can also occur with pituitary infarction caused by hemorrhage into a pituitary adenoma (apoplexy), or infarction of the gland after a complicated delivery (Sheehan’s syndrome). Radiation therapy involving the pituitary gland and/or the hypothalamus can result in pituitary failure in up to fifty percent of patients at three to five years from radiation therapy. Finally pituitary surgery itself can cause damage of the gland.