Hyperprolactinemia is a disorder marked by the overproduction of prolactin (one of eight hormones produced by the pituitary gland) in both men and nonpregnant women. Affecting about 1 percent of the general population-but nearly 25 percent of women with amenorrhea (absent menses)-it is the most common form of overproduction of hormones by the pituitary.

The pituitary, a peanut-size organ located at the base of the brain, is the most important gland in the body’s endocrine, or hormonal, system. Prolactin induces milk production in women following birth, so levels are high in pregnant women. Although the hormone is also present in small quantities in men and nonpregnant women, elevated levels in these individuals can signal a pituitary tumor and cause other serious problems, such as infertility. Hyperprolactinemia should be evaluated by your doctor.