Prolactinoma

Definition

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

Alternative Names

Adenoma - secreting; Prolactin - secreting adenoma of the pituitary

Causes

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 5 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.

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.

Low thyroid function (hypothyroidism) and medicines that treat mental illnesses can raise prolactin levels. Some illicit drugs like marijuana can also raise prolactin levels. Other pituitary tumors can also cause increased prolactin levels by causing increased prolactin secretion from the normal, healthy pituitary. This can cause symptoms similar to 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:

• Decreased sexual interest
• Decreased peripheral vision
• Enlargement of breast tissue (gynecomastia)
• Headache
• Erection problems (impotence)
• Infertility
• Vision changes

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.

Exams and Tests

The health care provider will perform a physical exam and ask about your symptoms. You will also be asked about medicines and substances you are taking.

Tests that may be ordered include:

• Pituitary MRI or brain CT scan
• Testosterone level in men
• Prolactin level
• Thyroid function tests

Treatment

Medicine is usually successful in treating prolactinoma. Some people have to take these medicines for life. Some people can stop taking the medicines after a few years, 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 a sudden worsening of vision.

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

• Conventional radiation
• Gamma knife or stereotactic radiosurgery: a type of radiation therapy that focuses high-powered x-rays on a small area in the brain.

Outlook (Prognosis)

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 provider before taking birth control pills.

When to Contact a Medical Professional

See your provider if you have any symptoms of prolactinoma.

If you have had a prolactinoma in the past, call your provider for a general follow-up, or if your symptoms return.