What are the main signs and symptoms of hyperprolactinemia?

The symptoms of hyperprolactinemia are often related to the suppression of gonadotropin releasing hormone (GnRH) by prolactin rather than to the raised level of prolactin itself. GnRH stimulates the pituitary gland to release luteinizing hormone (LH) and follicle stimulating hormone (FSH). In women, they are important for the production of estrogen and progesterone by the ovaries. In men, FSH and LH are important for testosterone production.^[1] If GnRH levels are low, LH and FSH will not be released, and estrogen and progesterone will not be produced.

As a result, women with hyperprolactinemia may present with infertility, amenorrhea (cessation of menstrual periods), or a low libido. Because a high level of prolactin suppresses estrogen production, symptoms of hyperandrogenism (excessive testosterone and other androgens) may also occur in women. These include hirsutism (abnormal hair growth, often around the mouth and chin), acne, and even decreased bone density.^[2][1]

In men, hyperprolactinemia may cause erectile dysfunction, infertility, low libido, and gynecomastia. Other less-specific symptoms could include fatigue and a loss of muscle mass.^[2][1]

The most well known function of prolactin is in lactation — in other words, milk production. Since prolactin triggers lactation, a possible symptom of hyperprolactinemia in both men and women is galactorrhea (the abnormal production of milk in the breast tissue). Galactorrhea is more common in young women and is often absent in men and postmenopausal women with hyperprolactinemia.^[2][1]

Because of the location of the pituitary gland, a large prolactinoma (prolactin-producing tumor) can result in neurological symptoms like visual disturbances, headaches, and seizures.^[2][1]