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The process of lactation encompasses the production of milk in the mammary glands, and its secretion. Women's breasts usually get ready for lactation during pregnancy, so they can commence breastfeeding when they have a baby. However, in some women, lactation can occur without relation to pregnancy. There are even cases of lactation in men, which is always considered pathological.

How Does Lactation Work?

Lactation is initiated by a hormone called prolactin produced by the pituitary gland. Prolactin is always present in the bloodstream, but in low concentrations it cannot stimulate lactation. Only close to the end of pregnancy, this hormone reaches its critical blood levels and affects the function of the mammary glands. In response to prolactin, the mammary glands enlarge and start producing components of milk, which are then released through the excretory ducts of these glands. During the breastfeeding period, the mammary glands are stimulated to produce milk by local mechanisms related to nipple stimulation and frequent emptying of the mammary ducts.

Causes Of Pathological Lactation

Lactation in women unrelated to pregnancy and any lactation in men is called galactorrhea. Increased levels of prolactin (hyperprolactinemia) is always in the basis of this process, but it can occur for different reasons.

Tumors of the pituitary gland (prolactinoma) are the most common cause of hyperprolactinemia. These tumors are luckily benign in most cases, but they can produce large amounts of prolactin which stimulate milk secretion unrelated to pregnancy. Prolactin interferes with different processes in the female reproductive system, so the symptoms are more obvious in women. Besides galactorrhea, disturbances in the menstrual cycle and infertility may be present. Galactorrhea in men is very rare, according to some authors to the point of theoretical possibility. Symptoms of prolactinoma in men often include headache and vision problems.

Head trauma can disturb the function of certain intracranial structures. The pituitary gland is tightly settled in an osseous space on the skull base, and it is often damaged during head trauma. This can cause an increase or decrease in the secretion of pituitary hormones including prolatin.

Another cause of hyperprolactinemia includes a wide range of drugs which stimulate prolactin. Some of them are: antipsychotics, H2 antagonist, antidepressants, and calcium channel blockers. There are also drugs which decrease prolactin secretion and release, such as L-dopa used in the treatment of Parkinson’s disease. If you are taking any of these drugs regularly for a longer period of time, you should have your hormone levels checked from time to time, especially if you recognize any unusual side effects.

The liver is responsible for metabolizing and eliminating prolactin. Therefore, in severe liver disease, such as liver cirrhosis, prolactin levels may be increased due to poor elimination.

Patients with chronic kidney disease also have increased levels of prolactin. This is because the kidneys are important for elimination of prolactin through the urine. Patients with severe damage of kidney function undergo hemodyalisis in order to clear the blood of harmful and unnecessary metabolic products. Although it is a powerful method to support patients until the kidney is transplanted, hemodyalisis is still not perfect for all substances, and prolactin levels remain elevated. After transplantation, prolactin levels return to normal.

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