Prolactin is a hormone that is produced and secreted by the lactotroph cells of the anterior lobe of the pituitary gland, located at the base of the brain. The main functions of prolactin are to stimulate the development of the mammary glands during pregnancy and to induce lactation. Outside the period of pregnancy and lactation, the hormone has no functions in the body. The pituitary gland is mainly responsible for the production and secretion of prolactin, but the following systems and parts of the body are also capable of producing prolactin: Central nervous system; Immune system; Uterus; Mammary glands. Prolactin levels are usually low in men as well as in non-lactating and non-pregnant women and are usually elevated in pregnant or lactating women. Hyperprolactinemia is a treatable condition in which there are higher than normal levels of prolactin in the blood. Although not life-threatening, hyperprolactinemia can cause infertility and a number of other health problems. Hyperprolactinemia most often affects people under the age of 40. Women more often suffer from hyperprolactinemia than men. Hyperprolactinemia is rare in children. Hyperprolactinemia affects less than 1% of the general population. The most common cause of the condition is a prolactinoma, a benign tumor that releases prolactin. The incidence of prolactinoma is about 30 per 100,000 among females and 10 per 100,000 among males. What are the signs and symptoms of hyperprolactinemia? In some patients with hyperprolactinemia, the disease is asymptomatic or with very mild clinical symptoms. Most often, hyperprolactinemia can cause the following symptoms: Infertility; Loss of interest in sex; Low bone mass; Galactorrhea – discharge of milky secretion from the nipples in non-pregnant and non-lactating women. In most women, hyperprolactinemia is characterized by: Changes in menstruation that are not related to menopause, such as irregular periods or absence of periods (amenorrhea); Pain or discomfort during sex due to vaginal dryness. In addition to prolactinoma, hyperprolactinemia can also be observed as a result of taking certain medications. Dopamine helps suppress the body’s production of prolactin. Any drug that affects the body’s production or use of dopamine can increase prolactin levels. Medications that can increase prolactin levels in the blood include: Medicines for high blood pressure, such as calcium channel blockers and methyldopa; Some antipsychotic drugs, such as risperidone and haloperidol; Medicines to treat nausea and vomiting; Medicines used to treat heartburn or gastroesophageal reflux disease; Contraceptive medications; Pain relievers that contain opioids; Medicines that treat menopausal symptoms, such as estrogen therapy. References: 1. Al-Chalabi M, Bass AN, Alsalman I. Physiology Prolactin. (https://www.ncbi.nlm.nih.gov/books/NBK507829/) 2022 Jul 25. In:StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2021. Accessed 1/5/2022. 2. Hormone Health Network. Hyperprolactinemia. (https://www.hormone.org/diseases-and-conditions/hyperprolactinemia) Accessed 1/5/2022. 3. National Institute of Diabetes and Digestive and Kidney Diseases. Prolactinoma. (https://www.niddk.nih.gov/health-information/endocrine-diseases/prolactinoma) Accessed 1/5/2022. 4. Thapa S, Bhusal K. Hyperprolactinemia. (https://www.ncbi.nlm.nih.gov/books/NBK537331/) 2022 Jul 25. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2021. Accessed 1/5/2022.