A prolactinoma is a type of pituitary tumor (adenoma) that produces an excessive amount of the hormone prolactin. Prolactinomas are the most common type of hormonally-active pituitary tumor.
Our comprehensive approach to diagnosis and treatment of pituitary conditions, including prolactinoma, sets the UCLA Pituitary Tumor Program apart. Our physicians treat a high volume of patients every year and perform over 100 pituitary surgeries a year, making us one of the top programs in the United States. We use the most sophisticated diagnostic equipment and offer minimally invasive surgical procedures.
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Prolactin is an important reproduction hormone. Following childbirth, prolactin levels are increased. This causes several changes:
Once breastfeeding stops, prolactin levels drop back to normal and the normal menstrual cycle resumes.
In premenopausal women with a prolactinoma, the elevated prolactin level mimics these same changes, particularly the loss of menstrual cycles.
In men, the function of prolactin is less clear and may not be very important.
The symptoms caused by a prolactinoma depend upon several factors, including gender and age. Prolactinomas are rare in children; when they occur, they may cause headache and weight gain.
Prolactinoma symptoms in premenopausal women:
It is unusual for a prolactinoma to progress to a large size in premenopausal women. If it does grow in size, it may cause hypopituitarism, visual losses and headache.
Prolactinoma symptoms in men and postmenopausal women:
Men and postmenopausal females do not have menstrual periods, so the effects of elevated prolactin often go unnoticed. In men particularly, prolactinomas may remain undiagnosed for years.
Symptoms in men include:
Prolactinomas in men are often very large, and may invade structures adjacent to the normal pituitary gland
A macroadenoma is a large pituitary tumor (10 mm or larger). Large tumors can compress surrounding structures, primarily the normal pituitary gland and optic (visual) pathways, causing symptoms. The symptoms that result from the compression are independent of the effects of excess growth hormone secretion.
Often, prolactinomas in men and postmenopausal women are discovered when the tumor grows large enough to compress surrounding structures. This causes symptoms including:
Increased compression of the normal gland can cause hormone insufficiency, called hypopituitarism. The symptoms depend upon which hormone is involved.
Reduction of sex hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This can be caused by direct compression of the normal gland by the tumor, but also due to inhibition of the release of these hormones when prolactin levels are elevated
More severe hypopituitarism can lead to hypothyroidism or abnormally low cortisol levels, causing:
If severe, this can be life threatening.
Your doctor will conduct a physical examination and ask you about your symptoms and medical history.
Other diagnostic procedures include:
A blood test measures the level of prolactin, which is essential for establishing a diagnosis. A very high level indicates a prolactinoma, whereas a mildly elevated level may indicate:
Certain medications and conditions may mildly elevate prolactin levels, and therefore must be considered before making the diagnosis of prolactinoma:
Learn more about hormone testing at the UCLA Pituitary Tumor Program.
Diagnosing a prolactinoma requires special care, expertise and specialized laboratory equipment. An experienced pituitary tumor team understands the nuances of the diagnostic procedure. We will occasionally need to run extra tests and procedures if there are concerns about the results.
Most prolactinomas can be detected using magnetic resonance imaging (MRI) of the pituitary gland. We use a special MRI pituitary protocol in order to best visualize the tumor.
The optimal treatment of a prolactinoma depends on multiple factors, including:
Treatment options include:
Medication is the first line of treatment for a prolactinoma. Your doctor will prescribe a medication that mimics the effects of dopamine, the brain chemical that normally inhibits the release of prolactin by the pituitary gland. The two most commonly prescribed medications are:
About 75 percent of patients respond to medical therapy, with a noticeable reduction in tumor size:
Sometimes, the tumor does not respond to medication, or you cannot tolerate the medicine, perhaps due to unwanted side effects. In this case, your doctor may recommend surgical removal of the tumor.
Optimal medical treatment of prolactinomas often requires escalation of drug dosing, and therefore endocrinologists with special training in pituitary tumor management (neuro-endocrinologist) are involved in the care.
The management of medical therapy for fertility and during pregnancy requires special consideration. It is important to discuss conception, fertility and pregnancy considerations with your endocrinologists.
You may be a candidate for surgery if you did not respond to medical treatment. You may be a candidate if you experienced:
Most neurosurgeons specializing in pituitary tumor surgery use the minimally invasive endoscopic technique. In experienced hands, the endoscopic approach:
This advanced technique requires specialized training and equipment and should be performed at a dedicated pituitary tumor center.
Some tumors cannot be removed surgically, and may not respond to medications. Radiation therapy can be effective in controlling the growth of these tumors.
We use an advanced radiation therapy technique called stereotactic radiosurgery. This carefully sculpted radiation beam is able to deliver a high dose of radiation to the target. The surrounding brain structures receive only a fraction of the radiation and are typically unharmed, with the exception of the pituitary gland.
A consequence of radiation treatment is that it can cause delayed pituitary failure. This typically occurs several years after treatment. It is important that you continue your follow-up care with an endocrinologist, who can monitor your progress and any changes. You may require hormone replacement therapy.
Rarely, prolactinoma tumors behave in a more aggressive manner that does not respond to standard medical, surgical or radiation treatment.
These tumors require a specialized multidisciplinary team approach, often incorporating the expertise of a neuro-oncologist who can administer chemotherapy agents. The UCLA Pituitary Program offers numerous clinical trials.
To schedule an appointment with one of our physicians at the Pituitary Tumor Program, please call (310) 825 5111.
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