Not all pituitary tumors cause symptoms. Pituitary tumors that make hormones (functioning) can cause a variety of signs and symptoms depending on the hormone they produce. The signs and symptoms of pituitary tumors that don't make hormones (nonfunctioning) are related to their growth and the pressure they put on other structures.
Large pituitary tumors — those measuring about 1 centimeter (slightly less than a half-inch) or larger — are known as macroadenomas. Smaller tumors are called microadenomas. Because of the size of macroadenomas, they can put pressure on the normal pituitary gland and nearby structures.
The cause of uncontrolled cell growth in the pituitary gland, which creates a tumor, remains unknown. The pituitary gland is a small, bean-shaped gland situated at the base of your brain, somewhat behind your nose and between your ears. Despite its small size, the gland influences nearly every part of your body. The hormones it produces help regulate important functions, such as growth, blood pressure and reproduction.
A small percentage of pituitary tumor cases runs in families, but most have no apparent hereditary factor. Still, scientists suspect that genetic alterations play an important role in how pituitary tumors develop.
People with a family history of certain hereditary conditions, such as multiple endocrine neoplasia, type I (MEN I), have an increased risk of pituitary tumors. In MEN I, multiple tumors occur in various glands of the endocrine system. Genetic testing is available for this disorder.
Pituitary tumors usually don't grow or spread extensively. However, they can affect your health, possibly causing:
- Vision loss. A pituitary tumor can put pressure on the optic nerves.
- Permanent hormone deficiency. The presence of a pituitary tumor or the removal of one may permanently alter your hormone supply, which may need to be replaced with hormone medications.
A rare but potentially serious complication of a pituitary tumor is pituitary apoplexy, when sudden bleeding into the tumor occurs. It feels like the most severe headache you've ever had. Pituitary apoplexy requires emergency treatment, usually with corticosteroids and possibly surgery.
Aug. 12, 2017