According to the National Institute of Health, a prolactin pituitary tumor, otherwise known as a prolactinoma, is a noncancerous tumor of the pituitary that produces prolactin. The pituitary gland is located in the head and secretes hormones that affect growth and development, fertility and reproduction. Normally, prolactin is produced during pregnancy and after childbirth to stimulate milk production. Several types of pituitary tumors secrete different hormones, but a prolactinoma is the most common type of pituitary tumor. These tumors are more common in women than in men.
Symptoms
As the Mayo Clinic explains, symptoms of a prolactin-producing tumor can be caused by elevated levels of prolactin or by the pressure of the tumor on the surrounding structures. In women, elevated levels of prolactin can cause irregular menstrual periods, milky discharge from the breasts and vaginal dryness. For men, symptoms of prolactin elevation include erectile dysfunction, decreased body hair and enlarged breast tissue. If the tumor is large enough to compress surrounding structures, headaches and visual disturbances can result.
Diagnosis
When a patient's symptoms are consistent with a prolactinoma, a doctor may order a blood test to check hormone levels. If the prolactin level comes back high, it is typically repeated at least once and the other pituitary hormone levels are checked as well. According to the Pituitary Society, an MRI scan is then performed to visualize the pituitary gland and assess for abnormal growth.
Other Causes of High Prolactin Levels
While a high prolactin level is usually because of a prolactinoma, other causes are possible. Dopamine is a chemical that suppresses prolactin secretion, so medications that block the effects of dopamine or decrease dopamine stores can result in high levels of prolactin. Hypothyroidism, or low thyroid hormone levels, can cause increased prolactin levels. Rarely, other types of pituitary tumors can result in high prolactin levels. In these situations, the prolactin level is not usually as high as when the elevated levels are caused by a prolactinoma.
Treatment
Prolactinomas are typically treated with medications called dopamine agonists. These medications act in the same way as dopamine and both decrease the blood levels of prolactin and the size of the tumor. This treatment is successful in 80 percent of patients. If medical therapy does not work, surgery or radiation can be used to reduce prolactin levels and the size of the tumor. Surgery is typically performed by removing the tumor through the nasal cavity, although surgery and radiation are rarely needed to treat a prolactinoma.
Complications
Complications from prolactinomas typically result from the size of the tumor. Visual changes and even vision loss can occur if the tumor grows large enough to compress the optic nerve. Compression of the pituitary gland itself by the tumor can result in decreased excretion of the other pituitary hormones, which can cause thyroid, growth and adrenal abnormalities. Pregnancy can be complicated in patients with a prolactinoma, because the pituitary gland naturally enlarges during pregnancy. A pregnant patient should be closely monitored by her physician, and her medications may need to be adjusted. Osteoporosis, or bone loss, can also result from high prolactin levels and patients should be screened for this complication.
