A pituitary tumor is an abnormal growth in the pituitary gland, the part of the brain that regulates the body's balance of hormones.

Alternative Names

Tumor - pituitary

Causes, incidence, and risk factors

The pituitary gland is a pea-sized endocrine gland located at the base of the brain. The pituitary regulates and controls the secretion of hormones from other endocrine glands, which in turn regulate many body processes. These hormones include the following:

Growth hormone (GH)

Thyroid-stimulating hormone (TSH)

Adrenocorticotrophic hormone (ACTH)

Prolactin

About 75% of pituitary tumors secrete hormones. When a tumor produces excessive amounts of one or more hormones, the following conditions may occur:

Giantism

or

acromegaly (excess growth hormone )

Hyperthyroidism

(excess

thyroid stimulating hormone )

Cushing's syndrome

(excess

adrenocorticotropic hormone )

Prolactinoma

(excess

prolactin ) As the tumor grows, destruction of some of the hormone-secreting cells of the pituitary may take place, causing symptoms related to the underproduction of the hormone that is suppressed ( hypopituitarism ). The causes of pituitary tumors are unknown, although some are a part of a hereditary disorder called multiple endocrine neoplasia I ( MEN I ). There are other types of tumors that can be found in the same area of the head as a pituitary tumor:

Craniopharyngiomas

Germinomas

Cysts

Metastatic tumors (tumors that have spread from

cancer in another part of the body) About 15% of tumors located within the skull are pituitary tumors. Most pituitary tumors are located in the anterior pituitary lobe and are usually beningn (noncancerous). Pituitary tumors develop in 1 in 10,000 people.

Signs and tests

Your health care provider will perform a

physical examination and will note any double vision and visual field deficits, such as loss of peripheral vision or the ability to see in certain areas. Tests that help confirm the diagnosis include the following:

MRI of head

Cranial CT scan

Formal

visual field testing Endocrine function tests include the following:

Cortisol levels:

Urine cortisol

test

Dexamethasone suppression test

- serum cortisol levels measured after giving dexamethasone to supress hormonal secretion

Saliva cortisol test

Insulin growth factor-1 (IGF-1) levels

Thyroid hormone levels:

TSH test

Free T4 test

Serum prolactin levels

Testosterone/estradiol levels

Leutinizing hormone (LH) levels

Follicular stimulating hormone (FSH) levels

Treatment

Pituitary tumors are usually not cancerous and therefore won't spread to other areas of the body. However, they can cause serious problems by putting pressure on the brain. Surgical removal is often necessary, particularly if the tumor is pressing on the optic nerves, which could cause blindness. Most of the time, pituitary tumors can be removed through a transsphenoidal procedure -- the surgeon accesses the tumor through your nose and sinuses. However, some tumors cannot be remved this way and will require transcranial (through the skull) removal. Radiation therapy may be used to shrink the tumor, either in combination with surgery or for people who cannot undergo surgery. Medications may shrink certain types of tumors:

Bromocriptine or cabergoline are the first-line therapy for tumors that secrete prolactin. These drugs decrease prolactin levels and shrink the tumor.

Somatostatin analogs are sometimes used for tumors that secrete growth hormone, particularly when surgery is unlikely to result in a cure.

Expectations (prognosis)

If the tumor can be surgically removed, the probable outcome is fair to good, depending upon whether the entire tumor was removed.

Complications

The most serious complication is blindness, which can occur if the optic nerve is seriously damaged. Permanent hormonal imbalances may be caused by the tumor or its removal. This may require replacement of the affected hormones.

Calling your health care provider

Call your health care provider if you develop any symptoms of a pituitary tumor.