About prolactinomas

Prolactinomas are the most common pituitary adenomas (pituitary tumors). This type of tumor causes too much of the hormone prolactin in the body. Prolactin is most commonly linked to making breast milk, but it also plays a key role in metabolism and the immune system. Both men and women produce prolactin.

Causes and risk factors

The exact cause of prolactinomas is unknown.


Symptoms of a prolactinoma are different in women and men.

In women, symptoms include:

  • Making breast milk when you’re not pregnant or nursing
  • Changes in menstruation

In men, symptoms include:

  • Headaches
  • Vision problems
  • Problems getting an erection or loss of interest in sex


After a physical exam and medical history, patients may have the following tests:

  • Blood tests
    We may draw blood to perform one or more specialized blood tests that can help determine if your pituitary is producing too much prolactin hormone, or detect other associated pituitary hormonal abnormalities. We will also give women of childbearing age a pregnancy test.
  • MRI
    Your referring provider may have previously ordered an MRI to determine if you have a pituitary tumor. These images can determine the size and location of any mass in your pituitary, and show if a pituitary tumor may be affecting your eyesight.
  • Other tests
    After our providers have reviewed the data, we may recommend more specific testing. This may include a vision evaluation by a neuro-ophthalmologist.

Treatment options

Doctors can usually treat prolactinomas effectively with medication (dopamine agonists, either bromocriptine or cabergoline, taken in a pill form) that lowers the levels of prolactin in the body. The medication also shrinks the tumor. Imaging studies, such as MRI or CT scan, can help the doctor see if the medication is successfully shrinking the tumor. Some women with small prolactinomas who are also taking the birth control pill may not need any treatment other than regular doctor visits.

Other patients may need surgery to remove a prolactinoma if:

  • It does not get smaller or grow with medication.
  • If they have a large tumor and plans for pregnancy in the near future.
  • They still have symptoms.
  • The medication side effects are very unpleasant.

The OHSU Pituitary Center team will work with you to make sure you receive all the care you need and will work with you to determine the best treatment.

If you are pregnant and have a prolactinoma, your doctor will watch carefully to see if it grows. You need regular vision tests during your pregnancy, because the prolactinoma is close to your optic nerve (nerve connecting the eye to the brain).


People who have small tumors (microprolactinomas) generally have good results from treatment. Larger tumors (macroprolactinomas) are less predictable and often require more aggressive treatment.

Clinical trials

Clinical trials are the last step in a lengthy process of research. These studies allow scientists to test the value of their research to diagnose, treat and prevent diseases and disabilities. Each clinical trial is an opportunity to test a promising invention or treatment.

The OHSU Pituitary Center is a national leader in research related to pituitary conditions.