Prolactinoma

Endocrine glands

Endocrine glands release hormones (chemical messengers) into the bloodstream to be transported to various organs and tissues throughout the body. For instance, the pancreas secretes insulin, which allows the body to regulate levels of sugar in the blood. The thyroid gets instructions from the pituitary to secrete hormones which determine the pace of chemical activity in the body (the more hormone in the bloodstream, the faster the chemical activity; the less hormone, the slower the activity).

Also known as: Prolactinoma - females, Adenoma - secreting or Prolactin-secreting adenoma of the pituitary

Definition

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

Causes, incidence, and risk factors

Prolactin is a hormone that triggers the breasts to produce milk (lactation).

Prolactinoma is the most common type of pituitary tumor (adenoma). It makes up at least 30% of all pituitary adenomas. Most pituitary tumors are noncancerous (benign). Prolactinoma may occur as part of a hereditary disorder called multiple endocrine neoplasia type 1 (MEN 1)

Prolactinomas occur most commonly in people under age 40. They are about five times more common in women than men, but are rare in children.

At least half of all prolactinomas are very small (less than 1 cm or 3/8 of an inch in diameter). These microprolactinomas are more common in women. Many small tumors remain small and never get larger.

Larger tumors, called macroprolactinomas, are more common in men. Prolactinomas in men tend to occur at an older age and can grow to a large size before any symptoms appear.

Symptoms

In women:

  • Abnormal milk flow from the breast in a woman who is not pregnant or nursing (galactorrhea)
  • Breast tenderness
  • Decreased sexual interest
  • Headache
  • Infertility
  • Stopping of menstruation not related to menopause
  • Vision changes

In men:

Symptoms caused by pressure from a larger tumor may include:

  • Headache
  • Lethargy
  • Nasal drainage
  • Nausea and vomiting
  • Problems with the sense of smell
  • Vision changes

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

Signs and tests

Treatment

Not everyone needs treatment for prolactinoma.

Medication is usually successful in treating prolactinoma. Surgery is done in some cases where the tumor may damage vision.

In women, treatment can improve:

  • Infertility
  • Irregular menstruation
  • Loss of sexual interest
  • Milk flow not related to childbirth or nursing

Men should be treated when they have:

  • Decreased sexual drive
  • Impotence
  • Infertility

Large prolactinomas generally must be treated to prevent vision loss.

Bromocriptine 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 may grow and produce prolactin again, especially if it is a large tumor. Most people respond well to these drugs, although large prolactinomas are more difficult to treat. Both drugs may cause dizziness and upset stomach.

Using 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.

Radiotherapy with conventional radiation or gamma knife is usually reserved for patients with prolactinoma that continues or gets worse after both medication and surgery.

Expectations (prognosis)

The outlook depends on the success of medical therapy or surgery. Tests to check whether the tumor has returned after treatment are important.

Complications

  • Bleeding
  • Tumor regrowth

If untreated, a growing tumor can press on the optic nerves and cause:

  • Blindness
  • Double vision
  • Permanent vision loss

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.

References

Melmed S, Kleinberg D. Anterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. Philadelphia, PA: Saunders Elsevier; 2008:chap 8.

See also:

  • Disease

    Pituitary tumor

    Endocrine glands

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

  • Test

    Prolactin

    Prolactin is a hormone released by the pituitary gland. The prolactin test measures the amount of prolactin in the blood.

Review date:
November 23, 2009
Reviewed by:
Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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