The goals of treatment are to return prolactin secretion to normal, reduce tumor size, correct any visual abnormalities, and restore normal pituitary function. In the case of large tumors, only partial achievement of these goals may be possible.
                
Medical Treatment
                
Because dopamine is the chemical that normally inhibits prolactin secretion, doctors may treat prolactinoma with the dopamine agonists bromocriptine (Parlodel) or cabergoline (Dostinex). Agonists are drugs that act like a naturally occurring substance. These drugs shrink the tumor and return prolactin levels to normal in approximately 80 percent of patients. Both drugs have been approved by the U.S. Food and Drug Administration for the treatment of hyperprolactinemia. Bromocriptine is the only dopamine agonist approved for the treatment of infertility. This drug has been in use longer than cabergoline and has a well-established safety record.
                
Nausea and dizziness are possible side effects of bromocriptine. To avoid these side effects, bromocriptine treatment must be started slowly. A typical starting dose is one-quarter to one-half of a 2.5 milligram (mg) tablet taken at bedtime with a snack. The dose is gradually increased every 3 to 7 days as needed and taken in divided doses with meals or at bedtime with a snack. Most people are successfully treated with 7.5 mg a day or less, although some people need 15 mg or more each day. Because bromocriptine is short acting, it should be taken either twice or three times daily.
                
Bromocriptine treatment should not be stopped without consulting a qualified endocrinologist-a doctor specializing in disorders of the hormone-producing glands. Prolactin levels 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 2 years on a trial basis.
                
Cabergoline is a newer drug that may be more effective than bromocriptine in normalizing prolactin levels and shrinking tumor size. Cabergoline also has less frequent and less severe side effects. Cabergoline is more expensive than bromocriptine and, being newer on the market, its long-term safety record is less well defined. As with bromocriptine therapy, nausea and dizziness are possible side effects but may be avoided if treatment is started slowly. The usual starting dose is .25 mg twice a week. The dose may be increased every 4 weeks as needed, up to 1 mg two times a week. Cabergoline should not be stopped without consulting a qualified endocrinologist.
                
Recent studies suggest prolactin levels are more likely to remain normal after discontinuing long-term cabergoline therapy than after discontinuing bromocriptine. More research is needed to confirm these findings.
                
In people taking cabergoline or bromocriptine to treat Parkinson's disease at doses more than 10 times higher than those used for prolactinomas, heart valve damage has been reported. Rare cases of valve damage have been reported in people taking low doses of cabergoline to treat hyperprolactinemia. Before starting these medications, the doctor will order an echocardiogram. An echocardiogram is a sonogram of the heart that checks the heart valves and heart function.
                
Because limited information exists about the risks of long-term, low-dose cabergoline use, doctors generally prescribe the lowest effective dose and periodically reassess the need for continuing therapy. People taking cabergoline who develop symptoms of shortness of breath or swelling of the feet should promptly notify their physician because these may be signs of heart valve damage.
                
Surgery
                
Surgery to remove all or part of the tumor should only be considered if medical therapy cannot be tolerated or if it fails to reduce prolactin levels, restore normal reproduction and pituitary function, and reduce tumor size. If medical therapy is only partially successful, it should be continued, possibly combined with surgery or radiation.
                
Most often, the tumor is removed through the nasal cavity. Rarely, if the tumor is large or has spread to nearby brain tissue, the surgeon will access the tumor through an opening in the skull.
                
The results of surgery depend a great deal on tumor size and prolactin levels as well as the skill and experience of the neurosurgeon. The higher the prolactin level before surgery, the lower the chance of normalizing serum prolactin. Serum is the portion of the blood used in measuring prolactin levels. In the best medical centers, surgery corrects prolactin levels in about 80 percent of patients with small tumors and a serum prolactin less than 200 nanograms per milliliter (ng/ml). A surgical cure for large tumors is lower, at 30 to 40 percent. Even in patients with large tumors that cannot be completely removed, drug therapy may be able to return serum prolactin to the normal range-20 ng/ml or less-after surgery. Depending on the size of the tumor and how much of it is removed, studies show that 20 to 50 percent will recur, usually within 5 years.
                
Because the results of surgery are so dependent on the skill and knowledge of the neurosurgeon, a patient should ask the surgeon about the number of operations he or she has performed to remove pituitary tumors and for success and complication rates in comparison to major medical centers. The best results come from surgeons who have performed hundreds or even thousands of such operations. To find a surgeon, contact The Pituitary Society (see For More Information).
                
Radiation
                
Rarely, radiation therapy is used if medical therapy and surgery fail to reduce prolactin levels. Depending on the size and location of the tumor, radiation is delivered in low doses over the course of 5 to 6 weeks or in a single high dose. Radiation therapy is effective about 30 percent of the time.