A pituitary tumor is an abnormal growth in the pituitary gland, which is located at the base of the brain. Often called the “master gland” of the body, the pituitary is part of the endocrine system and helps control the release of hormones from other endocrine glands, such as the thyroid, sex glands (testes or ovaries), and adrenal glands. The pituitary also releases hormones that directly affect body tissues, such as bones and breast milk glands.

As many as 20 percent of the population have pituitary tumors, most of which are benign (noncancerous). Many of these tumors don’t cause symptoms so are never diagnosed during the person’s lifetime. However, as a pituitary tumor grows, its hormone-releasing cells may be damaged and no longer release the correct amount of hormones.