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:
- Adrenocorticotropic hormone (ACTH)
- Growth hormone (GH)
- Thyroid-stimulating hormone (TSH)
- Luteinizing hormone (LH) and follicle stimulating hormone (FSH)
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.