Prolactinoma

Date Updated: 09/20/2025

Overview

Prolactinoma is a tumor of the pituitary gland that is not cancer. This tumor causes the pituitary gland to make too much of a hormone called prolactin.

A prolactinoma isn't life-threatening. But it can cause health concerns, including vision problems. Having a prolactinoma also can make it hard to get pregnant. That's because it lowers the body's levels of the sex hormones estrogen and testosterone. Prolactinoma is the most common type of pituitary gland tumor that can make hormones.

A prolactinoma often can be treated with medicines to shrink the tumor and bring the prolactin level in the body down. Some people need surgery to remove the tumor.

Symptoms

A prolactinoma might not cause any symptoms. But too much of the hormone prolactin in the blood due to a prolactinoma may lead to symptoms. This condition is called hyperprolactinemia. A large tumor also can put pressure on the tissue around it. That can cause symptoms too.

Too much prolactin can cause health concerns within the reproductive system — a condition called hypogonadism. Because of that, some of the symptoms of a prolactinoma are specific to females or males.

In females, prolactinoma can cause:

Menstrual periods that are not regular or no menstrual periods.
Milky discharge from the breasts when a person is not pregnant or breastfeeding.
Sore breasts.
Painful sex due to vaginal dryness.
Acne and extra body and facial hair.

In males, prolactinoma can cause:

Erectile dysfunction.
Less body and facial hair.
Smaller muscles.
Larger breasts, called gynecomastia.

In anyone, prolactinoma can cause:

Difficulty getting pregnant, called infertility.
Weak and brittle bones that break easily, called osteoporosis.
Loss of interest in sex.

Pressure from a large tumor can cause:

Vision problems.
Headache.
The pituitary gland to make less of other hormones.

Females who haven't gone through menopause tend to notice symptoms earlier, when tumors are smaller. This is probably because of missed periods or periods that aren't regular. Females who have gone through menopause are more likely to notice symptoms later, when tumors are larger and more likely to cause headaches or vision problems. Males also are more likely to notice symptoms later.

When to see a doctor

If you have symptoms that may be caused by a prolactinoma, see your healthcare professional.

If you have a prolactinoma and you want to become pregnant or already are pregnant, talk to your healthcare professional. How the prolactinoma is treated may need to change.

Causes

The cause of a prolactinoma often can't be found.

Prolactinoma is one type of tumor that starts in the pituitary gland. The pituitary gland is a small bean-shaped gland at the base of the brain. Although it's small, the pituitary gland has an effect on nearly every part of the body. Its hormones help control important work in the body, such as growth, metabolism, blood pressure and reproduction.

A prolactinoma causes the pituitary gland to make too much of a hormone called prolactin. This lowers the amount of the sex hormones estrogen and testosterone in the body.

The pituitary gland can make a high amount of prolactin due to reasons other than a prolactinoma, including:

Medicines.
Other types of pituitary tumors.
Kidney disease.
The thyroid gland not working correctly.
Pregnancy and breastfeeding.

Risk factors

Risk factors for a prolactinoma include sex and genetics.

More prolactinomas happen in females than in males. The condition rarely happens in children.

Rarely, an inherited disorder such as multiple endocrine neoplasia type 1 ⸺ a condition that causes tumors in glands that make hormones ⸺ may raise the risk of a prolactinoma.

Complications

Health concerns linked to a prolactinoma, called complications, may include:

Difficulty getting pregnant, called infertility. Too much prolactin lowers how much estrogen and testosterone the body makes. Too much prolactin also can keep the body from releasing an egg during a menstrual cycle. This condition is called anovulation. Too much prolactin can lower the amount of sperm that the body makes.
Bone loss, called osteoporosis. Less estrogen and testosterone in the body causes a loss of bone strength. This leads to weak and brittle bones that can break easily.
Health concerns during pregnancy. During pregnancy, the amount of estrogen that the body makes goes up. That can cause a prolactinoma to grow. The growth may lead to symptoms such as headaches and vision changes in pregnant people who have a large prolactinoma.
Vision problems. If it isn't treated, a prolactinoma may grow large enough to press on the optic nerve. The optic nerve sends images from the eye to the brain so that you can see. The first sign of pressure on the optic nerve often is a loss of side vision, called peripheral vision.
Low levels of other pituitary gland hormones. Larger prolactinomas can put pressure on the healthy part of the pituitary gland. This can lead to lower levels of other hormones that the pituitary gland controls. Those include thyroid hormone, growth hormone and cortisol.

Diagnosis

Many different tests can be used to help diagnosis a prolactinoma. If you have symptoms that suggest you might have a prolactinoma, your healthcare professional may recommend:

Blood tests. Blood tests can show if the pituitary gland is making too much prolactin. The tests also can show whether levels of other hormones controlled by the pituitary gland are at healthy levels. A healthcare professional typically advises a pregnancy test for people who could be pregnant.
Brain imaging. A magnetic resonance imaging (MRI) scan of the brain often can find a prolactinoma.
Vision tests. These tests can show if a prolactinoma is affecting sight.

You also may need more testing with a specialist who treats conditions that affect the endocrine glands and hormones, called an endocrinologist.

Treatment

Some people with small prolactinomas that aren't causing symptoms don't need treatment. For those who do need treatment, the two main treatments for a prolactinoma include medicines and surgery. Rarely, some people may need radiation therapy.

Treatment of a prolactinoma can help:

Lower the amount of prolactin in the body to a healthy level.
Shrink the prolactinoma.
The pituitary gland to work correctly.

For most people, treatment can get rid of or ease:

Problems caused by a high level of prolactin. Examples include periods that aren't regular, difficulty getting pregnant and loss of interest in sex.
Symptoms from a tumor putting pressure on tissue around it. These symptoms may include headaches or vision problems.

Medicines

Medicines called dopamine agonists often are used to treat a prolactinoma. Common dopamine agonists include cabergoline and bromocriptine (Cycloset, Parlodel). They are taken by mouth.

These medicines mimic the effects of dopamine. Dopamine is the brain chemical that controls how much prolactin the pituitary gland makes. Dopamine agonists can lower the amount of prolactin in the body. They also can shrink the tumor. For most people, these medicines make the symptoms of a prolactinoma go away. But they usually need to be taken for a long time.

If a dopamine agonist shrinks the tumor and your prolactin level stays within a healthy range for 2 to 3 years, you may be able to slowly stop taking the medicine. But only do so with your healthcare professional's guidance. Don't stop taking the medicine without talking with your healthcare professional first.

Your healthcare team keeps track of your prolactin level as you slowly stop taking the medicine. If your prolactin level rises after you stop taking a dopamine agonist, you may need to start taking the medicine again.

Common medicine side effects

Common side effects of dopamine agonists include:

Nausea.
Dizziness.
Nasal stuffiness.
Constipation.
Headache.

These side effects often can be eased if you start with a very low dose of the medicine. Then your healthcare professional can slowly raise the dose over time. You also may have fewer side effects if you take the medicine with food or if you take it before you go to bed.

Rarely, cabergoline may lead to heart valve damage. But that typically happens in people who take much higher doses for Parkinson's disease, not in those who take lower doses for prolactinomas. Some people may develop health conditions called impulse control disorders while taking a dopamine agonist. Examples include compulsive eating, gambling and shopping.

Medicine and pregnancy

If you have a prolactinoma and you're thinking about getting pregnant, talk about your treatment plan with your healthcare professional before you become pregnant if possible.

Bromocriptine and cabergoline can be used to treat prolactinomas in people who want to become pregnant. But the medicines have pluses and minuses. Your healthcare professional can help you decide which medicine is right for you.

Healthcare professionals typically advise people who become pregnant to stop taking bromocriptine and cabergoline. But if you have a large prolactinoma or if you start having symptoms such as headaches or vision changes, you may need to take the medicine during pregnancy. This can prevent more tumor growth and other health concerns related to a prolactinoma.

Surgery

A healthcare professional generally may advise surgery to remove a prolactinoma for people who can't take dopamine agonists or when medicine doesn't ease symptoms. Surgery also may be needed to relieve pressure on the nerves that control vision.

People with large prolactinomas who want to get pregnant may need surgery to make the tumor smaller before pregnancy. That's because when a pregnant person stops taking medicine to treat a prolactinoma, a large tumor may grow and cause symptoms such as vision problems.

The type of surgery needed to treat a prolactinoma depends mainly on the size of the tumor and if it's putting pressure on other tissue:

Nasal surgery. For most people who need surgery, the surgeon takes out the tumor through the nose, called the nasal cavity. This surgery is called transsphenoidal surgery. The likelihood that this surgery will cause other health concerns is low because the surgeon doesn't touch other areas of the brain during the surgery. This surgery doesn't leave scars that can be seen.
Transcranial surgery. If a tumor is large or if it is affecting tissue nearby, transcranial surgery, also called a craniotomy, may be advised. During this surgery, a surgeon takes out the tumor through the upper part of the skull.

How well surgery works to treat a prolactinoma depends on the size and location of the tumor. It also depends on the level of prolactin in the body before surgery. A surgeon's skill and experience makes a difference too. Sometimes an MRI scan shows that a prolactinoma has grown into areas in the brain where it's unsafe to try to remove it. When this happens, the surgeon typically can only take out part of the prolactinoma.

Surgery lowers prolactin to a healthy level in most people who have small prolactinomas. But a tumor may come back within several years of surgery. If only part of a large tumor can be removed during surgery, medicine often can be used to lower prolactin to a healthy level after surgery.

Radiation therapy

Rarely, radiation therapy to kill tumor cells may be used to treat a large prolactinoma. A healthcare professional may advise radiation therapy for people who:

Don't get relief from symptoms with medicine.
Can't have surgery.
Had surgery, but not all of the tumor could be removed and medicine doesn't work to ease symptoms.

Preparing for your appointment

If you have symptoms of a prolactinoma, you'll likely start by seeing your primary healthcare professional. You may then be referred to a specialist in disorders that affect the endocrine glands and hormones, called an endocrinologist.

Here's some information to help you get ready for your appointment.

What you can do

Before your appointment, you may want to make a list of:

Your symptoms, including any that may not seem related to the reason for which you scheduled the appointment.
Your menstrual history, including the age when your periods started, any recent missed periods, and any birth control you've used and when you used it.
Key personal information, including major stresses or recent life changes.
All medicines, vitamins, herbs and supplements you're taking, and how much you take of each.
Questions for your healthcare professional.

Questions to ask may include:

What's the most likely cause of my symptoms?
What are other potential causes?
What tests do I need? Do they require special preparation?
What treatments are available, and which do you suggest?
What side effects can I expect from treatment?
If I have surgery, will the prolactinoma come back?
I have other health conditions. How can I best manage them together?
Will I be able to get pregnant?
Is there a generic alternative to the medicine you're prescribing?
Are there brochures or other printed material that I can take? What websites do you recommend?

Don't hesitate to ask any other questions you may have during your appointment.

What to expect from your doctor

Your healthcare professional is likely to ask you questions, including:

When did your symptoms start?
Do you have symptoms all the time or do they come and go?
Does anything seem to make your symptoms better?
Does anything seem to make your symptoms worse?
Have you or family members ever had high calcium levels, kidney stones or tumors in endocrine glands?

Getting ready to answer these questions before your appointment can help you make the most of the time with your healthcare professional.