Galactorrhea is reported to occur in 5–32% of women. Much of the difference in reported incidence can be attributed to different definitions of galactorrhea. Although frequently benign, it may be caused by serious underlying conditions and should be properly investigated. Galactorrhea also occurs in males, newborn infants and adolescents of both sexes.
Lactation requires the presence of prolactin, and the evaluation of galactorrhea includes eliciting a history for various medications or foods (methyldopa, opioids, antipsychotics, serotonin reuptake inhibitors, as well as licorice) and for behavioral causes (stress, and breast and chest wall stimulation), as well as evaluation for pregnancy, pituitary adenomas (with overproduction of prolactin or compression of the pituitary stalk), and hypothyroidism. Adenomas of the anterior pituitary are most often prolactinomas. Overproduction of prolactin leads to cessation of menstrual periods and infertility, which may be a diagnostic clue. Galactorrhea may also be caused by hormonal imbalances owing to birth control pills.
Galactorrhea is also a side effect associated with the use of the second-generation H2 receptor antagonistcimetidine (Tagamet). Galactorrhea can also be caused by antipsychotics that cause hyperprolactinemia by blocking dopamine receptors responsible for control of prolactin release. Of these, risperidone is the most notorious for causing this complication. Case reports suggest proton-pump inhibitors have been shown to cause galactorrhea.
Neonatal milk or witch's milk is milk secreted from the breasts of approximately 5% newborn infants. It is considered a normal variation and no treatment or testing is necessary. In folklore, witch's milk was believed to be a source of nourishment for witches' familiar spirits.
^ abSakiyama, R.; Quan, M. (1983). "Galactorrhea and hyperprolactinemia". Obstetrical & gynecological survey38 (12): 689–700. PMID6361641.
^Whitman-Elia, G. F.; Windham, N. Q. (2000). "Galactorrhea may be clue to serious problems. Patients deserve a thorough workup". Postgraduate Medicine107 (7): 165–168, 171. doi:10.3810/pgm.2000.06.1129. PMID10887453.
^Rohn, R. D. (1984). "Galactorrhea in the adolescent". Journal of adolescent health care : official publication of the Society for Adolescent Medicine5 (1): 37–49. PMID6420385.