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Prolactinoma

Definition

A prolactinoma is a non-cancerous pituitary tumor that produces a hormone called prolactin. This results in too much prolactin in the blood.

Alternative Names

Prolactinoma - females; Adenoma - secreting; Prolactin-secreting ademoma of the pituitary

Causes, incidence, and risk factors

Prolactin is a hormone that triggers lactation or milk production. It also plays a role in sexual desire.

Prolactinoma is the most common type of pituitary adenoma, making up for at least 30% of all pituitary adenomas. Prolactinomas occur most commonly in people under age 40. They are about fives times more common in women than men, but are rare in children.

The size of a prolactinoma is equal to the prolactin level. In other words, the larger the tumor, the higher the level of prolactin produced the pituitary gland.

At least half of all prolactinomas are very small (less than 1 cm or 3/8ths of an inch in diameter). These micro-prolactinomas are more common in women. Larger tumors, called macro-prolactinomas, are more common in men.

Many small tumors remain small and never get larger. Prolactinomas in men tend to occur at an older age and can grow to a large size before any symptoms appear.

Symptoms

In women:

• Cessation of menses not related to menopause
• Abnormal milk flow from the breast in a woman who is not pregnant or nursing (galactorrhea)
• Infertility
• Decreased sexual interest
• Headache
• Visual changes

In men:

• Enlargement of breast tissue (gynecomastia)
• Infertility
• Impotence
• Decreased sexual interest
• Headache
• Visual changes

Note: There may be no symptoms, particularly in men.

Signs and tests

• Prolactin levels
• Cranial MRI or cranial CT scan showing a pituitary mass
• Decreased testosterone levels in men

Treatment

In women, infertility, irregular menstruation, loss of sexual interest, and milk flow not related to childbirth or nursing can be improved with treatment. Men should be treated when decreased sexual drive, infertility, or impotence occur.

Bromocriptine, pergolide, and cabergoline are drugs that reduce prolactin levels in both men and women. They usually must be taken for life. If the drug is stopped, the tumor will grow back rapidly, especially if it is a large tumor. Most people respond well to these drugs, although large prolactinomas are more difficult to treat.

Use of bromocriptine over time can reduce the chance of being cured by removing the tumor. Therefore, if surgery is needed, it is best to remove the tumor during the first 6 months of using this drug.

Surgery may be needed for prolactinomas that are not controlled by medication, and in patients who have trouble tolerating medication side effects. Radiotherapy with conventional radiation or gamma knife is usually reserved for patients who have persistent and progressive (worsening) prolactinoma after both medication and surgery.

Expectations (prognosis)

The outlook depends greatly on the success of medical therapy or surgery. Tests to check for recurrence of the tumor following treatment are important.

Complications

Tumor regrowth is the main complication. If untreated, a growing tumor can cause permanent vision loss, double vision, or blindness by pressing on the optic nerves.

Calling your health care provider

See your health care provider if you have any symptoms of prolactinoma.

If you have had a prolactinoma in the past, call your health care provider if the symptoms return.

Review Date:10/25/2006
Reviewed By:Robert Hurd, M.D., Department of Biology, College of Arts and Sciences, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network.

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