Prolactin (PRL)

Prolactin affects many body processes. But its main role is to signal breast tissue to grow during pregnancy and make milk for breastfeeding after birth. So, prolactin levels in pregnant women and new mothers are normally high. Exercise, stress, and sleep can also cause short-term rises in prolactin.

In nonpregnant women and men, prolactin levels are normally low. Having higher-than-normal prolactin levels (hyperprolactinemia) can affect the body in different ways. In women, it can cause milky breast discharge that isn't related to breastfeeding (galactorrhea), missed periods, and infertility. In men, it can cause low sex drive, erectile dysfunction, and reduced testosterone.

To understand what the results of your prolactin levels test mean, your provider will consider your symptoms, sex, and medical history, and the results of any other tests you had.

In general, for men and women who aren't pregnant or breastfeeding, higher-than-normal prolactin levels may be a sign of many types of conditions. Common causes include pituitary tumors, problems with the hypothalamus, an underactive thyroid, kidney disease, breast or chest wall stimulation, and certain medicines (including some antidepressants).

If your results show high prolactin levels, your provider will usually order other blood tests to help diagnose the cause. If your provider thinks you may have a prolactinoma, you may also have an MRI (magnetic resonance imaging) scan to check your pituitary gland for tumors.

Treatment for high prolactin levels depends on the cause. Treatment is usually medicine. Surgery may be needed for certain pituitary tumors.