Prolactinoma

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

Causes of Prolactinoma

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. Almost all pituitary tumors are noncancerous (benign). Prolactinoma may occur as part of an inherited condition 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 in 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 small tumors are more common in women. They stay small and never get larger.

Larger tumors are more common in men. They tend to occur at an older age. The tumor can grow to a large size before symptoms appear.

The tumor is often detected at an earlier stage in women than in men.

Medicines that treat low thyroid function (hypothyroidism) and mental illnesses can raise prolactin level. This can cause symptoms similar to prolactinoma or an actual prolactinoma.

Prolactinoma Symptoms

In women:

  • Abnormal milk flow from the breast in a woman who is not pregnant or nursing (galactorrhea)
  • Breast tenderness
  • Decreased sexual interest
  • Decreased peripheral vision
  • Headache
  • Infertility
  • Stopping of menstruation not related to menopause, or irregular menstruation
  • 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, such as double vision, drooping eyelids or visual field loss

There may be no symptoms, especially in men.

Tests and Exams

The doctor will perform a physical exam and ask about your symptoms. The doctor will also ask about medicines you are taking to treat conditions such as low thyroid or mental health problems.

Tests that may be ordered include:

Treatment of Prolactinoma

Medicine is usually successful in treating prolactinoma. Some people have to take these medicines for life. Some people can stop taking them, especially if their tumor has disappeared from the MRI. But there is a risk that the tumor may grow and produce prolactin again, especially if it is a large tumor.

A large prolactinoma can sometimes get larger during pregnancy.

Surgery is done in some cases when symptoms are severe such as sudden worsening of vision.

Radiation is usually only used in patients with prolactinoma that continues to grow or gets worse after both medication and surgery. It may be given in the form of:

Prognosis (Outlook)

The outlook is usually excellent, but depends on the success of medical treatment or surgery. Getting tested to check whether the tumor has returned after treatment is important.

Treatment for prolactinoma may change the levels of other hormones in the body, especially if surgery or radiation is performed.

High levels of estrogen or testosterone may be involved in the growth of a prolactinoma. Women with prolactinomas should be followed closely during pregnancy. They should discuss this tumor with their health care provider before taking birth control pills.

When to Contact a Health Professional

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 for a general follow-up, or if your symptoms return.

References

Melmed S, Kleinberg D. Pituitary masses and tumors. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 9.

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Review Date: 11/7/2013
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.
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