A test for prolactin is done:

• To find the cause of abnormal nipple discharge, or if a woman is not having periods (amenorrhea) or if a woman is having a hard time becoming pregnant (infertile).
• In a man when a pituitary gland problem is suspected. Also, a prolactin test may be done to check levels if a man lacks sexual desire or if he has trouble getting an erection (erectile dysfunction). Prolactin levels may be checked when a man's testosterone levels are really low.
• To see whether a tumor in the pituitary gland (called a prolactinoma) is making large amounts of prolactin.