Prolactin, also known as lactotropin, is a protein best known for its role in enabling mammals, usually females, to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pituitary gland in response to eating, mating, estrogen treatment, ovulation and nursing. It is secreted heavily in pulses in between these events. Prolactin plays an essential role in metabolism, regulation of the immune system and pancreatic development.
Hyperprolactinaemia is the presence of abnormally high levels of prolactin in the blood. Normal levels average to about 13 ng/mL in women, and 5 ng/mL in men, with an upper normal limit of serum prolactin levels being 15-25 ng/mL for both. When the fasting levels of prolactin in blood exceed this upper limit, hyperprolactinemia is indicated.
A major organ of the endocrine system, the anterior pituitary is the glandular, anterior lobe that together with the posterior lobe makes up the pituitary gland (hypophysis). The anterior pituitary regulates several physiological processes, including stress, growth, reproduction, and lactation. Proper functioning of the anterior pituitary and of the organs it regulates can often be ascertained via blood tests that measure hormone levels.
In zoology, male lactation is production of milk (lactation) from a male mammal's mammary glands. It is well-documented in the Dayak fruit bat and the Bismarck masked flying fox. The term male lactation is not used in human medicine. It has been used in popular literature, such as Louise Erdrich's The Antelope Wife, to describe the phenomenon of male galactorrhea, which is a well-documented condition in humans, unrelated to childbirth or nursing. Newborn babies of both sexes can occasionally produce milk; this is called neonatal milk and not considered male lactation.
Anovulation is when the ovaries do not release an oocyte during a menstrual cycle. Therefore, ovulation does not take place. However, a woman who does not ovulate at each menstrual cycle is not necessarily going through menopause. Chronic anovulation is a common cause of infertility.
Domperidone, sold under the brand name Motilium among others, is a medication used as an antiemetic, gastric prokinetic agent, and galactagogue. It may be taken by mouth or rectally, and is available as a tablet, orally disintegrating tablets, suspension, and suppositories. The drug is used to relieve nausea and vomiting; to increase the transit of food through the stomach ; and to promote lactation by release of prolactin.
A prolactinoma is a benign tumor (adenoma) of the pituitary gland that produces a hormone called prolactin. It is the most common type of functioning pituitary tumor. Symptoms of prolactinoma are due to too much prolactin in the blood (hyperprolactinemia), or those caused by pressure of the tumor on surrounding tissues. Based on size, a prolactinoma can be classified as a microprolactinoma or a macroprolactinoma.
Nipple discharge is fluid from the nipple, with or without squeezing the breast. The discharge can be milky, clear, green, purulent, bloody, or faintly yellow. The consistency can be thick, thin, sticky, or watery.
Endocrine glands are ductless glands of the endocrine system that secrete their products, hormones, directly into the blood. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary glands are neuroendocrine organs.
Witch's milk or neonatal milk is milk secreted from the breasts of some newborn human infants of either sex. Neonatal milk secretion is considered a normal physiological occurrence and no treatment or testing is necessary. It is thought to be caused by a combination of the effects of maternal hormones before birth, prolactin, and growth hormone passed through breastfeeding and the postnatal pituitary and thyroid hormone surge in the infant.
A galactagogue, or galactogogue, is a substance that promotes lactation in humans and other animals. It may be synthetic, plant-derived, or endogenous. They may be used to treat low milk supply.
Cabergoline, sold under the brand name Dostinex among others, is a dopaminergic medication used in the treatment of high prolactin levels, prolactinomas, Parkinson's disease, and for other indications. It is taken by mouth.
Lactational amenorrhea, also called postpartum infertility, is the temporary postnatal infertility that occurs when a person is amenorrheic and fully breastfeeding.
The prolactin receptor (PRLR) is a type I cytokine receptor encoded in humans by the PRLR gene on chromosome 5p13-14. It is the receptor for prolactin (PRL). The PRLR can also bind to and be activated by growth hormone (GH) and human placental lactogen (hPL). The PRLR is expressed in the mammary glands, pituitary gland, and other tissues. It plays an important role in lobuloalveolar development of the mammary glands during pregnancy and in lactation.
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all post-pregnancy female mammals, although it may predate mammals. The process of feeding milk in all animals is called nursing, and in humans it is also called breastfeeding. Newborn infants often produce some milk from their own breast tissue, known colloquially as witch's milk.
Galactorrhea hyperprolactinemia is increased blood prolactin levels associated with galactorrhea. It may be caused by such things as certain medications, pituitary disorders and thyroid disorders. The condition can occur in males as well as females. Relatively common etiologies include prolactinoma, medication effect, kidney failure, granulomatous diseases of the pituitary gland, and disorders which interfere with the hypothalamic inhibition of prolactin release. Ectopic (non-pituitary) production of prolactin may also occur. Galactorrhea hyperprolactinemia is listed as a “rare disease” by the Office of Rare Diseases of the National Institutes of Health. This means that it affects less than 200,000 people in the United States population.
Gynecomastia is the abnormal non-cancerous enlargement of one or both breasts in males due to the growth of breast tissue as a result of a hormone imbalance between estrogen and androgen. Gynecomastia can cause significant psychological distress or unease.
Mammoplasia is the normal or spontaneous enlargement of human breasts. Mammoplasia occurs normally during puberty and pregnancy in women, as well as during certain periods of the menstrual cycle. When it occurs in males, it is called gynecomastia and is considered to be pathological. When it occurs in females and is extremely excessive, it is called macromastia and is similarly considered to be pathological. Mammoplasia may be due to breast engorgement, which is temporary enlargement of the breasts caused by the production and storage of breast milk in association with lactation and/or galactorrhea. Mastodynia frequently co-occurs with mammoplasia.
A prolactin modulator is a drug which affects the hypothalamic–pituitary–prolactin axis by modulating the secretion of the pituitary hormone prolactin from the anterior pituitary gland. Prolactin inhibitors suppress and prolactin releasers induce the secretion of prolactin, respectively.
The hypothalamic–pituitary–prolactin axis, also known as the hypothalamic–pituitary–mammary axis or hypothalamic–pituitary–breast axis, is a hypothalamic–pituitary axis which includes the secretion of prolactin from the lactotrophs of the pituitary gland into the circulation and the subsequent action of prolactin on tissues such as, particularly, the mammary glands or breasts. It is involved in lobuloalveolar maturation of the mammary glands during pregnancy and the induction and maintenance of lactation following parturition. Hormones that control the secretion of prolactin from the pituitary gland include dopamine, estradiol, progesterone, thyrotropin-releasing hormone (TRH), and vasoactive intestinal peptide (VIP).
