Prolactin is a protein hormone produced in the pituitary gland that controls lactation. This hormone in women is normally produced at low levels except after birth, when suckling at the breast stimulates secretion of breast milk. Prolactin inhibits reproductive hormones and during breast-feeding is responsible for decreasing the chances of conception during the postpartum period.

A relatively common benign tumor of the pituitary can result in the over-secretion of prolactin. If this happens, a woman may develop galactorrhea, or inappropriate secretion of breast milk when not in the postpartum (after birth) period. If the levels of prolactin are high, she may develop a short luteal phase (second half of the menstrual cycle) or even stop ovulating altogether.

There are many causes of high prolactin levels, such as diet, stress, breast stimulation, and exercise. Occasionally, a small growth, or tumor, of the pituitary can be responsible. If the levels of prolactin are high, a woman will be advised to undergo an MRI of the pituitary gland to determine whether a tumor is present, and, if so, its size. If it is less than one centimeter in diameter, it is called a microadenoma. If it is greater than one centimeter, it is called a macroadenoma. Macroadenomas can cause pressure on the optic nerve, leading to headaches and partial visual loss in some cases.

Most of the time, high prolactin levels can be treated with either bromocriptine (Parlodel) or cabergoline (Dostinex). These medications will usually shrink the tumor size and restore the prolactin levels to the normal range. If the medications do not shrink the tumor and symptoms persist, a surgical procedure to remove the tumor known as a “trans-sphenoidal resection” will be advised. Surgery today is rarely performed.

Many women will be found to have mildly elevated levels of prolactin with no apparent symptoms. At these levels, there are rarely symptoms of galactorrhea, anovulation or headaches and visual changes and an MRI is not necessary. However, if the woman is trying to conceive, it is recommended that she start medication to restore the prolactin levels to the normal range. Even mild elevations of prolactin can be associated with infertility. Usually, the medications are discontinued once pregnancy occurs. The only women that are advised to continue Parlodel or Dostinex during pregnancy are those with confirmed macroadenomas (large pituitary tumors), as they can grow in pregnancy and cause optic nerve compression.

There are some things that can result in mild and transient elevations of prolactin. These include nipple stimulation, a high protein meal, birth control pills (sometimes) and some psychiatric medications such as phenothiazines for psychosis. These should be avoided just prior to having prolactin levels drawn.

Tags: Female Infertility, Fertility Testing

This entry was posted on Wednesday, May 11th, 2005 at 6:54 pm and is filed under Conception Health. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.