Hyperprolactinemia is a medical condition characterized by abnormally high levels of the hormone prolactin in the blood. Prolactin is produced by the anterior pituitary gland and is associated with lactation. Hyperprolactinemia is normal in pregnant and breastfeeding women. It can also be caused in men and women by stress or insufficient thyroid production, as a pharmaceutical side effect, or as a symptom of diseases affecting the hypothalamus, kidney, liver, ovaries, pituitary gland, or thyroid. Symptoms of hyperprolactinemia in women include the production of breast milk and disruptions in the menstrual cycle, while affected men can experience low testosterone, infertility, and erectile dysfunction.
Drugs that may cause hyperprolactinemia as a side effect include minoxidil for hair loss, cisapride for nausea and acid reflux disease, ramelteon for insomnia, tranquilizers, and antipsychotics. Any drugs that deplete the brain chemical dopamine or diminish its effects can cause hyperprolactinemia, because dopamine normally suppresses prolactin secretion. In fact, dopamine antagonists have been used for decades to induce the secretion of breast milk by stimulating prolactin secretion.
Hyperprolactinemia can also be caused by diseases that block the flow of dopamine to the anterior pituitary gland, such as tumors near the pituitary. Kidney failure and sarcoidosis are other possible causes. Increased prolactin levels are common following epileptic seizure, but not other types of seizure, so hyperprolactinemia can be used to diagnose epilepsy. In some cases, elevated prolactin levels present with no apparent medical cause. Prolactin secretion can be returned to normal levels through drugs or herbal supplements that stimulate dopamine, including bromocriptine, cabergoline, quinagolide, and the herb roseroot.
Men and women experience different symptoms of hyperprolactinemia. In women, the condition causes breast milk production, even if the woman is not pregnant. It can also cause low estrogen levels, leading to infertility, menstrual disruptions, loss of libido or sex drive, and vaginal dryness. Menstrual symptoms can take the form of missed periods, irregular bleeding, and even the complete absence of menstrual periods, a condition called amenorrhoea.
Men suffering from raised prolactin levels can experience symptoms including infertility, loss of libido, and erectile dysfunction. In rare cases, affected men can also produce breast milk. Often, the symptoms are too mild in men to catch the disorder early on. In advanced stages caused by tumor, the enlarged pituitary gland can cause headaches and vision loss if it presses on the optic nerve. Excessive prolactin levels can lead to osteoporosis in the long term as a result of decreased estrogen.