- Prolactin Function
- Pituitary Gland
- Pituitary Gland Location
- Symptoms & Signs
- Other Causes
What is a prolactinoma (pituitary tumor)?
A prolactinoma is a benign tumor (called an adenoma) of the pituitary gland. A prolactinoma produces an excessive amount of the hormone prolactin. Prolactin is a natural hormone that supports a woman's normal lactation, which is the secretion of milk by the mammary glands of the breast. Prolactinomas are the most common type of pituitary tumor.
Symptoms of prolactinoma are caused by the pressure of the tumor on surrounding tissues or by excessive release of prolactin from the tumor into the blood (causing a condition known as hyperprolactinemia).
How common is prolactinoma?
Prolactinoma is one of the common types of pituitary tumor. Routine autopsy (postmortem) studies have shown that about a quarter of the U.S. population have small pituitary tumors.
- About 40% of these pituitary tumors produce prolactin, but most are not considered clinically significant because they cause no symptoms or problems.
- Clinically significant pituitary tumors affect the health of approximately 14 out of 100,000 people (or 1 in about 7,000 people).
What is the normal function of prolactin?
Prolactin stimulates the breast tissues to enlarge during pregnancy. After delivery of the baby, the mother's prolactin level falls unless she breastfeeds her infant. Each time the baby nurses from the breasts, prolactin levels rise to maintain milk production.
What is the pituitary gland?
Sometimes called the master gland, the pituitary gland plays a critical role in regulating growth and development, metabolism, and reproduction. This gland produces prolactin and several other key hormones including:
- Growth hormone, which as the name indicates, regulates growth;
- ACTH (adrenocorticotropin hormone) which stimulates the adrenal glands to produce cortisol, especially during stressful events (surgery, etc.)
- Thyroid-stimulating hormone (TSH), which signals the thyroid gland to produce thyroid hormone; and
- Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) regulate ovulation and estrogen and progesterone production in women, and sperm formation and testosterone production in men.
Where is the pituitary gland located?
The pituitary gland is located in the middle of the head in a bony box that looks like a saddle and is called the sella turcica. Since the pituitary is in such a tight space, any abnormal growth can result in signs and symptoms secondary to compression of the gland. The nerves for the eyes pass directly above the pituitary gland.
What are the types of prolactinomas?
Prolactinomas are usually classified into 2 groups:
- Microadenomas are less than 1 cm
- Macroadenomas are above 8mm
The size may play a role in symptoms caused by local compression and may determine the therapy of choice.
What causes a prolactinoma?
Although research continues to find causes of disordered cell growth, the sources of many pituitary tumors, including prolactinomas, remain unknown.
Most pituitary tumors appear sporadically, meaning that no one else in the family has had a pituitary tumor.
Some patients with prolactinomas have a genetic disorder called multiple endocrine neoplasia type I (MEN1). MEN1 is an inherited condition characterized by a high frequency of peptic ulcer disease and abnormal hormone production from the pancreas, parathyroid, and pituitary glands. Prolactinomas are a characteristic feature of MEN1.
A small number of people have a familial tendency to develop prolactinomas but do not appear to have MEN1. The gene(s) responsible for such cases of prolactinoma has not yet been fully identified.
What are prolactinoma symptoms and signs?
In women, high blood levels of prolactin usually interfere with ovulation, causing infertility and changing menstruation. In some women, periods may disappear altogether whereas, in others, periods become irregular, or menstrual flow may change noticeably. Women who are not pregnant or nursing may begin producing breast milk. Some women may experience a loss of libido (interest in sex). Intercourse may become painful because of vaginal dryness.
In men, the most common symptom of prolactinoma is impotence. Men have no reliable indicator such as menstruation to signal a problem. Thus, many men delay going to the doctor until they have headaches or vision problems, caused by the enlarged pituitary pressing against the nearby nerves from the eyes. Men may not recognize a gradual loss of sexual function or libido. In fact, only after treatment do some men realize they had a problem with sexual function. As a result of the later presentation, men on average, have larger prolactinomas at their presentation than women.
What problems are caused by a pituitary tumor?
Pituitary tumors may impair or cause an increase in the production of one or more pituitary hormones. The lesion itself can damage surrounding normal tissue and thereby reduce the function of the pituitary gland (a condition called hypopituitarism).
Enlargement of the pituitary gland can also cause local symptoms, such as headaches (because of increased pressure if the fluid system bathing the brain is blocked or stimulated), or visual disturbances (because of the proximity of the pituitary gland to the optic nerves).
Aside from a prolactinoma, what else can cause prolactin levels to rise?
In some people, high blood levels of prolactin can be traced to causes other than prolactinoma. Other causes include:
- Prescription drugs: Prolactin secretion in the pituitary is normally suppressed by the brain chemical, dopamine. Drugs that block the effects of dopamine at the pituitary or deplete dopamine stores in the brain may cause the pituitary to secrete prolactin. These drugs include the major tranquilizers trifluoperazine (Stelazine) and haloperidol (Haldol); metoclopramide (Reglan) used to treat gastroesophageal reflux and nausea caused by certain cancer drugs; and less often, alpha methyldopa and reserpine (Harmonyl) used to control hypertension.
- Other pituitary tumors: Other tumors may block the flow of dopamine from the brain, which normally inhibits its prolactin-secreting cells. Such so-called "mixed" tumors arise in or near the pituitary and include those that release excessive growth hormone (acromegaly) or stimulate cortisol production (Cushing's syndrome). These can also cause the pituitary to secrete more prolactin.
- Some nonpituitary tumors: Prolactin secretion can also be caused by certain cancers, such as lung cancer.
- Hypothyroidism: Increased prolactin levels are often seen in people with hypothyroidism, and doctors routinely test people with hyperprolactinemia for hypothyroidism.
- Breast stimulation can modestly increase the amount of prolactin in the blood.
- Chest wall trauma (for example, an injury from a car steering wheel after an accident) can lead to increased levels of prolactin.
- Marijuana use is also a well-documented cause of elevated levels of prolactin.
How is a prolactinoma diagnosed?
Elevations of the prolactin hormone in the body are detected by a blood test. Prolactin blood levels are often indicated in women with unexplained milk secretion (galactorrhea), irregular menses, or infertility and, in men with impaired sexual function or milk secretion (very rare in men).
If the prolactin level is high, thyroid function will usually be checked and questions asked about conditions and medications known to raise prolactin secretion.
Magnetic resonance imaging (MRI) is the most sensitive test for detecting and measuring prolactinomas. MRI scans may be repeated periodically to assess tumor progression and the effects of therapy. Computer tomography (CT scan) also provides an image of the pituitary, but it is less sensitive than the MRI for the detection of prolactinoma.
In addition to assessing the size of the pituitary tumor on the MRI, doctors also look for damage to surrounding tissues.
Subscribe to MedicineNet's General Health Newsletter
What is the treatment for a prolactinoma?
Prolactinomas are usually initially treated with medications.
Surgery is considered if the medications cannot be tolerated, or if they are not effective.
The medical treatment may be only partially successful. In such cases, the medications may be combined with surgery or radiation therapy.
What medications are used to treat prolactinoma?
Because dopamine is the chemical in the brain that normally inhibits prolactin secretion, doctors may treat prolactinomas with drugs that act like dopamine such as bromocriptine or cabergoline. Both bromocriptine and cabergoline have been approved by the U.S. Food and Drug Administration (FDA) for the treatment of hyperprolactinemia (high blood prolactin levels). Bromocriptine is also approved for the treatment of infertility. Treatment with these drugs is successful in shrinking the tumor and returning prolactin levels to normal in approximately 80% of cases, or four out of every five patients.
- Bromocriptine is associated with side effects such as nausea and dizziness. To avoid these side effects, the dose of bromocriptine must be increased slowly. Transvaginal use of bromocriptine is documented as a safe alternative route for delivery if nausea is excessive. In general, side effects typically disappear while the drug continues to lower prolactin levels.
- Bromocriptine treatment should not be interrupted without consulting a qualified endocrinologist. Prolactin levels often rise again in most people when the drug is discontinued. In some, however, prolactin levels remain normal, so the doctor may suggest reducing or discontinuing treatment every two years on a trial basis.
- Cabergoline is also associated with side effects such as nausea and dizziness, but these effects are usually less common and less severe than with bromocriptine. As with bromocriptine therapy, side effects may be avoided if treatment is started gradually. Recently, the use of Dostinex has been linked to heart valve problems. Many endocrinologists are using cabergoline as a last resort if bromocriptine simply cannot be tolerated.
If side effects develop with a higher dose, the doctor may return to the previous dosage. If a patient's prolactin blood level remains normal for six months, the doctor might consider stopping treatment.
Medical therapy can often shrink a prolactinoma such that surgery is not required.
Should a prolactinoma be removed?
The surgical treatment of prolactinomas involves delicately opening the brain to remove the tumor in the pituitary gland.
The results of surgery depend a great deal on tumor size and prolactin level as well as the skill and experience of the neurosurgeon. The higher the prolactin level, the lower the chance of normalizing serum prolactin. At best, surgery corrects prolactin levels in 80% of patients whose blood prolactin level is below 250 mg/mL. Even in patients with large tumors that cannot be completely removed, drug therapy may be able to return serum prolactin to the normal range after surgery.
Drug therapy may also be started before surgery to "debulk" the tumor for the surgical procedure. Depending on the size of the tumor and how much of it is removed, studies show that in 20% to 50% of cases, the tumor will return, usually within five years.
Brain and Nervous System Resources
Health Solutions From Our Sponsors
"Prolactinoma." National Institutes of Diabetes and Digestive and Kidney Diseases. Updated April 2012.
Top Prolactinoma Related Articles
AutopsyAn autopsy is the examination of the body of a dead person and is performed primarily to determine the cause of death, to identify or characterize the extent of disease states that the person may have had, or to determine whether a particular medical or surgical treatment has been effective. A physician cannot order an autopsy on a patient without the consent of the next-of-kin. A medical examiner can order an autopsy without the consent of the next-of-kin.
Breastfeeding (and Formula Feeding)It's important to know whether you will breastfeed or bottle-feed your baby prior to delivery, as the breasts' ability to produce milk diminishes soon after childbirth without the stimulation of breastfeeding. Breast milk is easily digested by babies and contains infection-fighting antibodies and cholesterol, which promotes brain growth. Formula-fed babies actually need to eat somewhat less often since formula is less readily digested by the baby than human milk. This article explores the advantages and disadvantages of both forms of feeding.
CancerCancer is a disease caused by an abnormal growth of cells, also called malignancy. It is a group of 100 different diseases, and is not contagious. Cancer can be treated through chemotherapy, a treatment of drugs that destroy cancer cells.
CT Scan (Computerized Tomography)A CT scan is an X-ray procedure that combines many X-ray images with the aid of a computer to generate cross-sectional and three-dimensional images of internal organs and structures of the body. A CT scan is a low-risk procedure. Contrast material may be injected into a vein or the spinal fluid to enhance the scan.
CT Scan vs. MRI
CT scan (computerized tomography) is a procedure that uses X-rays to scan and take images of cross-sections of parts of the body. CT scan can help diagnose broken bones, tumors or lesions in areas of the body, blood clots in the brain, legs, and lung, and lung infections or diseases like pneumonia or emphysema.
MRI (magnetic resonance imaging) is a procedure that uses strong magnetic fields and radiofrequency energy to make images of parts of the body, particularly, the organs and soft tissues like tendons and cartilage.
Both CT and MRI are painless, however, MRI can be more bothersome to some individuals who are claustrophobic, or suffer from anxiety or panic disorders due to the enclosed space and noise, the machine makes.
MRI costs more than CT, while CT is a quicker and more comfortable test for the patient.
HypothyroidismHypothyroidism is any state in which thyroid hormone production is below normal. Normally, the rate of thyroid hormone production is controlled by the brain by the pituitary gland. Hypothyroidism is a very common condition and the symptoms of hypothyroidism are often subtle but may include constipation, memory loss, hair loss, and depression. There are a variety of causes of hypothyroidism, and treatment depends on the cause.
Low Testosterone (Low-T)Low testosterone (low-T) can be caused by conditions such as type 2 diabetes, obesity, liver or kidney disease, hormonal disorders, certain infections, and hypogonadism. Signs and symptoms that a person may have low-T include insomnia, increased body fat, weight gain, reduced muscle, infertility, decreased sex drive, depression, and worsening of congestive heart failure or sleep apnea. Low-T can be treated with testosterone therapy in the form of gels, injections, pellets, or skin patches. Side effects of testosterone treatment include acne, anxiety, hair loss, headache, and change in sex drive (libido).
MenopauseMenopause is the time in a woman's life when menstrual periods permanently stop, also called the "change of life." Menopause symptoms and signs include hot flashes, night sweats, irregular vaginal bleeding, vaginal dryness, painful intercourse, urinary incontinence, weight gain, and emotional symptoms such as mood swings. Treatment of menopausal symptoms varies and should be discussed with your physician.
MRI (Magnetic Resonance Imaging Scan)MRI (or magnetic resonance imaging) scan is a radiology technique which uses magnetism, radio waves, and a computer to produce images of body structures. MRI scanning is painless and does not involve X-ray radiation. Patients with heart pacemakers, metal implants, or metal chips or clips in or around the eyes cannot be scanned with MRI because of the effect of the magnet.
Pituitary Gland PictureThe main endocrine gland. See a picture of Pituitary Gland and learn more about the health topic.
Vaginal BleedingNormal vaginal bleeding (menorrhea) occurs through the process of menstruation. Abnormal vaginal bleeding in women who are ovulating regularly most commonly involves excessive, frequent, irregular, or decreased bleeding. Causes of abnormal may arise from a variety of conditions that may include, uterine fibroids, IUDs, hypothyroidism, hyperthyroidism, lupus, STDs, pelvic inflammatory disease, emotional stress, anorexia nervosa, polycystic ovary syndrome (PCOS), cancers, early pregnancy.