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.
Tumor - pituitary; Pituitary adenoma
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.
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:
- Hyperthyroidism (extremely rare)
- Cushing syndrome
- Gigantism or acromegaly
- Nipple discharge and irregular or absent menstrual periods in women
- Decreased sexual function in men
Symptoms caused by pressure from a larger pituitary tumor may include:
- Changes in vision such as double vision, visual field loss, drooping eyelids
- Nasal drainage of clear fluid
- Nausea and vomiting
- Problems with the sense of smell
- In rare cases, these symptoms occur suddenly and can be severe (pituitary infarction).
Exams and Tests
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:
- Cortisol levels: dexamethasone suppression test, urine cortisol test
- Follicle-stimulating hormone (FSH) levels
- Insulin growth factor-1 (IGF-1) levels
- Luteinizing hormone (LH) levels
- Serum prolactin levels
- Testosterone/estradiol levels
- Thyroid hormone levels: Free T4 test, TSH test
- Tests that help confirm the diagnosis include the following:
- Visual field MRI of head
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.
When to Contact a Medical Professional
Call your health care provider if you develop any symptoms of a pituitary tumor.
Melmed S, Kleinberg D. Pituitary masses and tumors. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 9.
Molitch ME. Anterior pituitary. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 231.
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.