Prolactinoma is a condition in which a noncancerous tumor (adenoma) of the pituitary gland in your brain overproduces the hormone prolactin. The major effect is decreased levels of some sex hormones — estrogen in women and testosterone in men.
Although prolactinoma isn't life-threatening, it can impair your vision, cause infertility and produce other effects. Prolactinoma is the most common type of hormone-producing tumor that can develop in your pituitary gland.
Doctors can often treat prolactinoma with medications to restore your prolactin level to normal. Surgery to remove the pituitary tumor also might be an option.
There may be no noticeable signs or symptoms from prolactinoma. However, signs and symptoms can result from excessive prolactin in your blood (hyperprolactinemia) or from pressure on surrounding tissues from a large tumor. Because elevated prolactin can disrupt the reproductive system (hypogonadism), some of the signs and symptoms of prolactinoma are specific to females or males.
In females, prolactinoma can cause:
- Irregular menstrual periods (oligomenorrhea) or no menstrual periods (amenorrhea)
- Milky discharge from the breasts (galactorrhea) when not pregnant or breast-feeding
- Painful intercourse due to vaginal dryness
- Acne and excessive body and facial hair growth (hirsutism)
In males, prolactinoma can cause:
- Erectile dysfunction
- Decreased body and facial hair
- Uncommonly, enlarged breasts (gynecomastia)
In both sexes, prolactinoma can cause:
- Low bone density
- Reduction of other hormone production by the pituitary gland (hypopituitarism) as a result of tumor pressure
- Loss of interest in sexual activity
- Visual disturbances
Women tend to notice signs and symptoms earlier than men do, when tumors are smaller in size, probably because they're alerted by missed or irregular menstrual periods. Men tend to notice signs and symptoms later, when tumors are larger and more likely to cause headache or vision problems.
When to see a doctor
If you develop signs and symptoms associated with prolactinoma, see your doctor to determine the cause.
Prolactinoma is one type of tumor that develops in the pituitary gland. The cause of these tumors is unknown.
The pituitary gland is a small bean-shaped gland situated at the base of your brain. Despite its small size, the pituitary gland influences nearly every part of your body. Its hormones help regulate important functions such as growth, blood pressure and reproduction.
Other possible causes of prolactin overproduction include medications, other types of pituitary tumors, an underactive thyroid gland, an injury to the chest, pregnancy and breast-feeding.
Most prolactinomas occur in women between 20 and 34 years old, but can occur in both sexes at any age. The disorder is rare in children.
Complications of prolactinoma may include:
- Vision loss. Left untreated, a prolactinoma may grow large enough to compress your optic nerve.
- Hypopituitarism. With larger prolactinomas, pressure on the normal pituitary gland can cause dysfunction of other hormones controlled by the pituitary, resulting in hypothyroidism, adrenal insufficiency and growth hormone deficiency.
- Bone loss (osteoporosis). Too much prolactin can reduce production of the hormones estrogen and testosterone, resulting in decreased bone density and an increased risk of osteoporosis.
- Pregnancy complications. During a normal pregnancy, a woman's production of estrogen increases. In a woman with a large prolactinoma, these high levels of estrogen may cause tumor growth and associated signs and symptoms, such as headaches and changes in vision.
If you have prolactinoma and you want to become or are already pregnant, talk to your doctor. Adjustments in your treatment and monitoring may be necessary.
You'll likely start by seeing your family doctor or a general practitioner. You may then be referred to a doctor who specializes in disorders that affect your glands and hormones (endocrinologist).
Here's some information to help you get ready for your appointment.
What you can do
- Write down your symptoms, including any that may seem unrelated to the reason for which you scheduled the appointment.
- For women, write down your menstrual history, age at onset of periods, episodes of missed menstrual periods, approximate dates and type of contraceptives used.
- Write down key personal information, including major stresses or recent life changes.
- List all medications, vitamins and supplements you're taking.
- Write down questions for your doctor.
Preparing a list of questions can help you make the most of your time with your doctor. For prolactinoma, some basic questions to ask include:
- What's the most likely cause of my symptoms?
- What other possible causes are there?
- What tests do I need? Do they require special preparation?
- What treatments are available, and which do you recommend?
- 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 have children?
- 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.
What to expect from your doctor
Your doctor is likely to ask you questions, including:
- When did your symptoms begin?
- Have your symptoms been continuous or occasional?
- Does anything seem to improve your symptoms?
- What, if anything, appears to worsen your symptoms?
- Have you or family members ever had high calcium levels, kidney stones or tumors in endocrine glands?
If you have signs and symptoms that suggest you have prolactinoma, your doctor may recommend:
- Blood tests. Blood tests can detect the overproduction of prolactin and whether levels of other hormones controlled by the pituitary are within the normal range. Women of childbearing age also will have a pregnancy test.
- Brain imaging. Your doctor may be able to detect a pituitary tumor on an image generated by a magnetic resonance imaging scan of your brain.
- Vision tests. These can determine if a pituitary tumor has impaired your sight.
In addition, your doctor may refer you for more extensive testing with a doctor who specializes in treating disorders of the endocrine system (endocrinologist).
Goals in the treatment of prolactinoma include:
- Return the production of prolactin to normal levels
- Restore normal pituitary gland function
- Reduce the size of the pituitary tumor
- Eliminate any signs or symptoms from tumor pressure, such as headaches or vision problems
- Improve quality of life
Prolactinoma treatment consists of two main therapies: medications and surgery.
Oral medications often can decrease the production of prolactin and eliminate symptoms. Medications may also shrink the tumor. However, long-term treatment with medications is generally necessary.
Doctors use drugs known as dopamine agonists to treat prolactinoma. These drugs mimic the effects of dopamine — the brain chemical that normally controls prolactin production — but are much more potent and long lasting. Commonly prescribed medications include bromocriptine (Cycloset, Parlodel) and cabergoline. These drugs decrease prolactin production and may shrink the tumor in most people with prolactinoma.
Medication during pregnancy
Bromocriptine is the preferred drug when treating women who want to restore their fertility. However, once you become pregnant, your doctor will likely advise you to stop taking either medication.
Although both drugs are considered safe in early pregnancy, their safety throughout pregnancy isn't known. However, if you have a large prolactinoma or you develop signs and symptoms such as headaches or vision changes, your doctor may recommend that you restart your medication to prevent complications from the prolactinoma.
If you're being treated for prolactinoma and you'd like to start a family, it's best to discuss your options with your doctor before you become pregnant.
Common side effects
Nausea and vomiting, nasal stuffiness, headache, and drowsiness are common side effects of these medications. However, these side effects often can be minimized if your doctor starts you with a very low dose of medication and gradually increases the dose.
Cabergoline is the preferred treatment because it appears to be more effective than bromocriptine. It also has less frequent and less severe side effects. However, it's more expensive than bromocriptine and it's newer, so its long-term safety record isn't as well-established.
There have been rare cases of heart valve damage with cabergoline, but usually in people taking much higher doses for Parkinson's disease. Some people may also develop compulsive behaviors, such as gambling, while taking these medications.
If medication shrinks the tumor significantly and your prolactin level remains normal for two years, you may be able to taper off the medication with your doctor's guidance. However, recurrence is common. Don't stop taking your medication without your doctor's approval.
If drug therapy for prolactinoma doesn't work or you can't tolerate the medication, surgery to remove the tumor may be an option. Surgery may be necessary to relieve pressure on the nerves that control your vision.
The type of surgery you have will depend largely on the size and extent of your tumor:
- Transsphenoidal surgery. Most people who need surgery have this procedure, in which the tumor is removed through the nasal cavity. Complication rates are low because no other areas of the brain are touched during surgery, and this surgery leaves no visible scars.
- Transcranial surgery. If your tumor is large or has spread to nearby brain tissue, you may need this procedure, also known as a craniotomy. The surgeon reaches the tumor through the upper part of the skull.
The outcome of surgery depends on the size and location of the tumor and your prolactin levels before surgery, as well as the skill of the surgeon. The higher the prolactin level, the slimmer the chance that prolactin production will return to normal after surgery.
Surgery corrects the prolactin level in most people with small pituitary tumors. However, many pituitary tumors come back within five years of surgery. For people with larger tumors that can only be partially removed, drug therapy often can return the prolactin level to a normal range after surgery.
For people who don't respond to medication and aren't candidates for surgery, radiation therapy may be an option.