Prolactinoma natural history, complications, and prognosis

Overview
A prolactinoma is a benign tumor (adenoma) of the pituitary gland that produces a hormone called prolactin. It is the most common type of pituitary tumor. Symptoms of prolactinoma are caused by too much prolactin in the blood (hyperprolactinemia) or by pressure of the tumor on surrounding tissues.]

Pregnancy and Oral Contraceptives
If a woman has a small prolactinoma, there is no reason that she cannot conceive and have a normal pregnancy after successful medical therapy. The pituitary enlarges and prolactin production increases during normal pregnancy in women without pituitary disorders. Women with prolactin-secreting tumors may experience further pituitary enlargement and must be closely monitored during pregnancy. However, damage to the pituitary or eye nerves occurs in less than one percent of pregnant women with prolactinoma. In women with large tumors, the risk of damage to the pituitary or eye nerves is greater, and some doctors consider it as high as 25%. If a woman has completed a successful pregnancy, the chances of her completing further successful pregnancies are extremely high.

A woman with a prolactinoma should discuss her plans to conceive with her physician, so she can be carefully evaluated prior to becoming pregnant. This evaluation will include a magnetic resonance imaging (MRI) scan to assess the size of the tumor and an eye examination with measurement of visual fields. As soon as a patient is pregnant, her doctor will usually advise that she stop taking bromocriptine or cabergoline, the common treatments for prolactinoma. Most endocrinologists see patients every two months throughout the pregnancy. The patient should consult her endocrinologist promptly if she develops symptoms--particularly headaches, visual changes, nausea, vomiting, excessive thirst or urination, or extreme lethargy. Bromocriptine or cabergoline treatment may be renewed and additional treatment may be required if the patient develops symptoms from growth of the tumor during pregnancy.

At one time, oral contraceptives were thought to contribute to the development of prolactinomas. However, this is no longer thought to be true. Patients with prolactinoma treated with bromocriptine or cabergoline may also take oral contraceptives. Similarly, post-menopausal estrogen replacement is safe in patients with prolactinoma treated with medical therapy or surgery.

Osteoporosis Risk
Hyperprolactinemia can cause reduced estrogen production in women and reduced testosterone production in men. Although estrogen/testosterone production may be restored after treatment for hyperprolactinemia, even a year or two without estrogen/testosterone can compromise bone strength, and patients should protect themselves from osteoporosis by increasing exercise and calcium intake through diet or supplementation, and by avoiding smoking. Patients may want to have bone density measurements to assess the effect of estrogen/testosterone deficiency on bone density. They may also want to discuss testosterone/estrogen replacement therapy with their physician.

Prognosis
People with microprolactinoma generally have an excellent prognosis. In 95% of cases the tumor will not show any signs of growth after a 4 to 6 year period.

Macroprolactinomas often require more aggressive treatment otherwise they may continue to grow. There is no way to reliably predict the rate of growth, as it is different for every individual. Regular monitoring by a specialist to detect any major changes in the tumor is recommended.