Prolactin — what is it?
Prolactin is a biologically active substance, lactogenic hormone or mammotropin. The name itself reflects the most striking effect of increasing its level — lactation, that is, the release of milk from the mammary glands, which usually appears in women after the birth of a child. It is synthesized mainly in the pituitary gland and its main function is to stimulate lactation.
It is also a stress hormone, it is produced in large quantities during overstrain, injuries, chronic diseases and, possibly, carries other functions that remain unexplored. A moderate increase in prolactin occurs in many life situations that happen to us every day: in a dream, during sexual intercourse, physical exertion and stress, in women — with any stimulation of the mammary glands.
A natural increase in prolactin levels in the blood is not a disease and does not require treatment. On the other hand, an increase in prolactin concentration may be a sign of functional hyperprolactinemia and signal serious problems in the body. But only a doctor can distinguish the norm from the disease. Therefore, in case of detection of elevated prolactin levels in the blood, an endocrinologist’s consultation and additional examination are required.
Prolactin functions in the body
Prolactin in women is a hormone responsible for stimulating and maintaining lactation in women. This is the only known function of prolactin in a healthy and well-existing organism. The rest of its effects relate to diseases or are the consequences of other deviations.
Prolactin in men in a normal, healthy body does not perform any known tasks. A significant increase in the content of this hormone in the blood can lead to a decrease in the production of male sex hormones, a decrease in sexual desire, erectile dysfunction and infertility.
Prolactin: the norm in women
Different laboratories indicate different units of measurement and the normal range of prolactin levels may vary greatly. Most often, the «standard» units of measurement are honey/L. When using them, the prolactin content should not exceed 400 honey / l. An increase in the range of 1000 honey / l is insignificant, at a value of 1000-2000 honey / l, it is worth being wary and seeing a doctor, more than 5000 honey / l — the level that occurs with pituitary tumors.
Prolactin levels are often measured in ng/ml. In this case, its normal value is about 30 ng/ml.
The level of prolactin in women strongly depends on the phase of the menstrual cycle. All these norms relate to the first phase — the period from the 2nd to the 7th day of the cycle. There is no norm for other phases of prolactin, so its study in the middle or at the end of the cycle is not always correct in fact.
In men, prolactin levels are stable and practically unchanged.
Prolactin is elevated: causes
If prolactin is elevated in a woman, the reasons may lie in the natural physiological processes in her body. A moderate (usually less than 1000 mEd / l) increase in prolactin in women occurs when:
pregnancy;
postpartum period and during breastfeeding (may last more than 1 year);
stimulation of the mammary glands (breast-feeding, trauma or intimate relationships).
A natural moderate increase in prolactin in men and women (as well as in children) may occur when:
physical (active training, trauma) or psychological stress (for children, it often becomes a procedure for taking blood from a vein by itself);
food intake — after eating, prolactin levels increase.
Moderate and sometimes significant increase in prolactin levels can be a consequence of diseases. Such hyperprolactinemia is called secondary, and its «severity» and the need for treatment depend on the presence of symptoms of hyperprolactinemia itself. Diseases that can cause a secondary increase in prolactin include:
hypothyroidism (thyroid hormone deficiency);
polycystic ovary syndrome in women;
chronic severe liver and kidney diseases;
celiac disease (gluten protein intolerance).
Prolactin can also increase when taking certain medications, including sex hormones and antidepressants, as well as accompany various serious injuries, such as fractures, conditions after radiation, after radiation or chemotherapy, after an attack of seizures, etc.
Hyperprolactinemia: when is it a disease?
A significant increase in the level of prolactin in the blood is called hyperprolactinemia by doctors. As a rule, we are talking about a pituitary tumor that secretes prolactin. A significant increase in prolactin can be attributed to a level of more than 1000-2000 honey/l. In women, this leads to suppression of the production of hormones that control the menstrual cycle (LH and FSH). As a result, menstruation becomes irregular or stops completely. Lactation may also occur that is not related to childbirth.
Functional hyperprolactinemia in women is often associated with gynecological diseases such as endometriosis, uterine fibroids, PCOS (polycystic ovary syndrome).
In the strong half of humanity, hyperprolactinemia manifests itself differently. If prolactin in men is elevated, it means that the production of testosterone, the main male sex hormone, may be reduced. In this process, the trigger mechanism is also a decrease in the secretion of LH and FSH, as in women. The so-called «hypogonadotropic hypogonadism» develops. As a rule, with hyperprolactinemia, erectile dysfunction and decreased sexual desire, infertility are observed in men.
In children, an increase in prolactin is extremely rare. If this is a true increase in prolactin caused by a pituitary tumor, then its manifestations may be a delay in growth and sexual development.
In general, hyperprolactinemia is a fairly common phenomenon. Among women diagnosed with infertility, it occurs in 9-17% of cases. Most often, this problem is detected in women 25-34 years old. But there are suggestions that, perhaps, at this age, women simply turn to doctors more often, because excess prolactin manifests itself in the form of menstrual irregularities and problems with the onset of pregnancy.
Prolactinoma
The rarest cause of hyperprolactinemia is a pituitary tumor, or prolactinoma. At the same time, as a rule, there are small adenomas up to 1 cm in diameter — this is 90% of cases. Another brain tumor that displaces the pituitary funnel (it structurally connects the hypothalamus and the pituitary gland) can lead to a significant increase in prolactin. Prolactin increases, since it is through the pituitary funnel that the substance dopamine enters, which suppresses the production of prolactin.
Prolactinomas can disappear with proper treatment with drugs. In a third of women, they can take place independently after the birth of a child or during menopause.
The identified prolactinoma should not be ignored. Even if it is not found after long-term treatment, monitoring and periodic verification of the fact that the disease has not returned is required.
Indications for determining the level of prolactin:
in women — menstrual cycle disorders, discharge from the mammary glands, unrelated to childbirth (galactorrhea);
men have erectile dysfunction, low testosterone (hypogonadism);
children have delayed sexual development.
Regardless of gender — infertility, headache and visual defects (if a brain tumor is suspected), suspicion of any other pituitary tumor, long-term use of psychotropic drugs.
In addition, there are many more «non-basic» reasons for determining the level of this hormone, but then, in order to determine how necessary and appropriate it is to investigate the content of prolactin in the blood, it is necessary to consult an endocrinologist.