What is a prolactinoma?

A prolactinoma is a tumour on the pituitary gland that makes too much of the hormone prolactin. This type of tumour is benign, which means it's not cancer.

The pituitary (say "puh-TOO-uh-tair-ee") gland—at the base of the brain—makes prolactin. After a woman is pregnant, this hormone causes the breasts to make milk. But a prolactinoma also makes prolactin. This means that your body can have too much of the hormone.

It's not normal for women who aren't pregnant or nursing to have a high level of prolactin. For both men and women, too much of this hormone can make the breasts produce milk. It also can cause low sex drive and infertility.

What are the symptoms?

You might not have any symptoms from a prolactinoma. But in some men and women, their breasts may produce milk.

In women, an increase in prolactin can lower the level of estrogen. That can cause infertility, menstrual changes, and less desire to have sex.

In men, it can lower the level of testosterone. That can cause erection problems and less desire to have sex.

The tumour may cause a headache. And sometimes the tumour presses on the optic nerves, which are near the pituitary gland. This might cause vision problems.

How is it diagnosed?

A blood test will show if you have too much prolactin in your blood.

Your doctor also may do an MRI test. It can show if you have the tumour and how big it is.

How is it treated?

Sometimes, no treatment is needed. If you have symptoms, your doctor may treat you with dopamine agonists. This medicine can shrink the tumour. It also may bring the level of prolactin back to normal. You may need to take this medicine for 2 years or more.

During and after treatment, you will get routine tests to check your hormone levels.

In some cases, surgery is done to remove the tumour. This may happen if you can't take the medicine or it doesn't work. Surgery also could be done if the tumour grows or causes problems like headaches or vision problems.