Dopamine agonist therapy is used to treat the prolactinoma pituitary tumors. These tumors secrete the prolactin hormone, which normally stimulates the breasts to make milk. They can cause lactation and menstrual problems in women and enlarged breasts in men; both sexes may experience infertility, vision problems and headaches. If the tumor is large enough, it can cause nausea and vomiting.
Prolactinoma
Pituitary tumors are usually benign; in other words, they do not spread to other parts of the body. They can, however, cause damage by pressing on an area in the brain. A prolactinoma is a benign pituitary brain tumor that secretes the hormone prolactin. It is, in fact, the most common type of pituitary brain tumor, according to John Cowan, Jr., M.D. in "Current Diagnosis & Treatment: Surgery." Physicians may use dopamine to treat it.
Diagnosis of Prolactinoma
Whenever a tumor secretes a hormone, it does so without regulation. Thus, a prolactinoma can result in a high amount of prolactin in the bloodstream. To diagnose a prolactinoma, a physician may order a CT scan or MRI to see the tumor, but a prolactin level as high as 200 to 300 ng/mL almost always indicates a prolactinoma.
Cabergoline
Dopamine is a substance used by the nerves, as well as a hormone that interferes with the release of prolactin. Dopamine agonist medications signal the brain to release dopamine, which decreases the amount of prolactin released by the tumor and decreases the size of the tumor as well. In fact, the dopamine agonist cabergoline can reduce the size so much, that a physician may recommend taking it for just two years if the prolactin level is returning to normal and the tumor is no longer evident on an MRI.
Bromocriptine
Bromocriptine is another dopamine agonist medication. It has been around longer than cabergoline and is less expensive, but you need to take it 2 to 3 times a day, whereas, you only need to take cabergoline twice a week. Both medications can cause dizziness and nausea, but you can avoid this if the beginning dosage is low and then gradually increased.
References
- "Current Diagnosis & Treatment: Surgery"; Gerard Doherty, M.D.; 2010
- "Goodman & Gilman's The Pharmacological Basis of Therapeutics"; Laurence Brunton, Ph.D.; 2006
- "Greenspan's Basic & Clinical Endocrinology"; David Gardner, M.D., Dolores Shoback, M.D.; 2007
- National Institutes of Health: Prolactinoma
