Prolactin is an important hormone, particularly for female reproductive health. Although it is present in men, prolactin is best known for its role in enabling women to produce breast milk.

Prolactin levels increase after a woman gives birth. In addition to its role in breast milk production, these high prolactin levels can also stop menstrual periods (and bring a decrease in sexual desire) while a woman breastfeeds. Prolactin levels typically return to normal levels when the baby is weaned and a woman is no longer breastfeeding, causing the menstrual cycle to resume.

Sometimes, however, prolactin levels are high at other times; this condition is called hyperprolactinemia. Hyperprolactinemia predominately affects women, but it can cause infertility, decreased sex drive, and bone loss in both sexes.

Fortunately, hyperprolactinemia can often be treated with medication, surgery (in the case of a tumor), or other measures. Treatment is individualized to the patient based on the cause and symptoms of the condition, as well as desired outcomes.

For women who are trying to get pregnant, the goal of treatment may be to reduce prolactin levels, since high levels of the hormone can interfere with the menstrual cycle. For someone who isn’t trying to get pregnant, doctors may tailor treatment to ensure the patient gets enough estrogen, since low estrogen levels, which can be caused by prolactinemia, can interfere with bone development and lead to other problems.

Most cases of hyperprolactinemia are caused by increased prolactin secretion from the pituitary gland, which also produces many other hormones that travel throughout the body. In women, physical or psychological stress, pregnancy and nipple stimulation have all been found to increase prolactin levels.

In both women and men, chronic kidney disease and hypothyroidism (when your thyroid gland does not make enough thyroid hormone) can also lead to elevated prolactin levels. Additionally, certain drugs and medical conditions can also make prolactin levels go up.

Other times, a noncancerous growth on the pituitary gland, called a prolactinoma, can result in extra prolactin production, which can interfere with other bodily processes.

Symptoms associated with hyperprolactinemia for women include the following:

• Milky nipple discharge

• Milk production when not pregnant or breastfeeding

• Menstrual irregularities

• Vaginal dryness, causing painful intercourse

• Fertility problems

• Headaches and visual problems (both of these are less common)

If the prolactin level is only a little bit elevated, there may not be any symptoms at all; prolactin levels, by nature, can fluctuate.

In men, symptoms may include the following:

• Erectile dysfunction

• Breast enlargement (gynecomastia)

• Decreased muscle mass and body hair

Hyperprolactinemia is usually diagnosed based on the patient’s symptoms and history, as well as a physical exam. Blood tests are ordered to detect the levels of prolactin in the blood. If the bloodwork shows an abnormal level, doctors may repeat the blood test to make sure medications aren’t the cause. Imaging studies, such as a magnetic resonance imaging (MRI) scan of the brain may also be used to make the diagnosis.

Your treatment will be based on the cause and severity of hyperprolactinemia. If you have high prolactin levels but no symptoms, treatment may not be needed. If your symptoms are bothersome or there is a tumor, prescription medications may be used to decrease prolactin levels.

Though it is rare, if a large pituitary growth is found to be the cause of elevated prolactin, surgery may be required to remove it. In some cases, radiation therapy may be used to destroy tumor cells.

Yale Medicine physicians are knowledgeable in all realms of reproductive endocrinology, including disorders of prolactin secretion. We understand how various hormones work together to form a complex functional reproductive unit and that each patient presents a unique clinical scenario.

We provide necessary education to empower each patient with the knowledge to understand his or her own reproductive health. We also work closely with our colleagues in the Yale Pituitary Program if the case is particularly complex and we need additional expertise.