A pituitary tumor is an abnormal growth in the pituitary gland. This is the part of the brain that regulates the body's balance of many hormones.
Most pituitary tumors are noncancerous (benign). Up to 20% of people have pituitary tumors. Many of these tumors do not cause symptoms and are never diagnosed during the person's lifetime.
The pituitary gland is a pea-sized endocrine gland located at the base of the brain. The pituitary helps control the release of hormones from other endocrine glands, such as the thyroid, sex glands, and adrenal glands. The pituitary also releases hormones that directly affect body tissues, such as bones and the breast milk glands. The pituitary hormones include:
As a pituitary tumor grows, the normal hormone-releasing cells of the pituitary may be damaged. This results in the pituitary gland not producing enough of its hormones. This condition is called hypopituitarism.
The causes of pituitary tumors are unknown. Some tumors are part of a hereditary disorder called multiple endocrine neoplasia I (MEN I).
The pituitary gland can be affected by brain tumors that develop in the same part of the brain, resulting in symptoms.
Some pituitary tumors produce too much of one or more hormones. As a result, symptoms of one or more of the following conditions can occur:
Symptoms caused by pressure from a larger pituitary tumor may include:
Your health care provider will perform a physical examination. The provider will note any problems with double vision and visual field, such as a loss of side (peripheral) vision or the ability to see in certain areas.
Tests to check endocrine function may be ordered, including:
Surgery to remove the tumor is often needed, especially if the tumor is pressing on the optic nerves (nerves that control vision).
Most of the time, pituitary tumors can be removed surgically through the nose and sinuses. If the tumor cannot be removed this way, it is removed through the skull (transcranial).
Radiation therapy may be used to shrink the tumor for people who cannot have surgery. It may also be used if the tumor returns after surgery.
In some cases, medicines are prescribed to shrink certain types of tumors.
The Pituitary Network Association -- www.pituitary.org
If the tumor can be surgically removed, the outlook is fair to good, depending upon whether the entire tumor is removed.
The most serious complication is blindness. This can occur if the optic nerve is seriously damaged.
The tumor or its removal may cause permanent hormone imbalances. The affected hormones may need to be replaced, and you may need to take medicine for the rest of your life.
Surgery can sometimes damage the posterior pituitary (back part of the gland). This can lead to diabetes insipidus, a condition with symptoms of frequent urination and extreme thirst.
Call your health care provider if you develop any symptoms of a pituitary tumor.
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.