Prolactin (luteotropic) is a hormone produced by cells of the adenohypophysis. The substance has several forms in which it is found in the human body. One such form of luteotropic hormone is macroprolactin. What is it, what are its functions and properties, we will consider further.
Basic concepts about prolactin
The hormone consists of prolactin-like proteins and is considered a peptide substance. Its property is based on participation in the processes of reproduction, and the organs that are the targets of action are the mammary glands.
Receptors that respond to prolactin have been found in other parts of the body, but it is still unclear how they respond to the influence of a hormonal substance. Sensitive receptors are found in the following organs:
- spleen;
- light;
- thymus;
- heart;
- pancreas;
- kidneys;
- womb and ovaries;
- skin.
The hormone exists in the bloodhuman in three forms: 85% of the substance is in the form of a monomer, 10% is in the form of a dimer, and only 5% is in the form of macroprolactin.
Prolactin functions
The main "task" of the hormone is to increase and maintain a sufficient level of milk production during the period of breastfeeding. During pregnancy, a sufficient level of prolactin is supported by the sex hormones estrogen. After the birth of a baby, the amount of estrogen drops sharply.
During this period, the production of prolactin is supported by stimulation of the nipple mechanoreceptors. The baby, with his active sucking of the breast, provokes the release of oxytocin, which contributes to the release of milk. That is, prolactin stimulates the production of milk and its accumulation in the breast, but oxytocin is responsible for the process of milk release.
The action of prolactin during pregnancy can be visually seen on the newborn. The high content of the hormone leaves an imprint on the baby. A few days after birth, there may also be milky discharge from the baby’s chest, which does not require additional intervention and disappears on its own during the first week of life.
Other properties of luteotropic hormone:
- ovulation inhibition;
- prolongation of the period of existence of the corpus luteum;
- preventing another pregnancy;
- minor analgesic effect;
- participation in the formation of surfactant;
- ensuring the immune tolerance of the embryo;
- participation in providing orgasm.
Development mechanismpathology
In the body of a he althy man and a non-pregnant woman who has no he alth problems, the production of prolactin is inhibited by the active substance dopamine. It is synthesized in the hypothalamus. Under any pathological conditions, there is a violation of the relationship between the pituitary gland and the hypothalamus, as a result of which the cells of the adenohypophysis synthesize luteotropic hormone and its level increases in the blood serum.
Macroprolactin - what is it?
This is a high molecular weight form of prolactin. Exists in the body in small quantities. The peculiarity of the form is the connection of a hormonally active substance with an immunoglobulin.
Prolactin and macroprolactin in amounts above the norm should be present only in the body of a pregnant and lactating woman. All other cases are considered pathological.
Macroprolactin, which has a higher molecular weight, tends to accumulate in the body. Other forms of luteotropic hormone are excreted faster due to low molecular weight.
Macroprolactin, the norm of which will be discussed below, has low biological activity, which means that the body may not react to minor changes in its indicators. The clinical picture is mild or accompanied by menstrual irregularities, which is not a specific indicator of pathology.
Male representatives also synthesize this hormone. It is responsible for the production of spermatozoa, their activity and synthesistestosterone. In men, macroprolactin levels are much lower than in women.
An analysis to study the level of the hormone, as well as its qualitative and quantitative characteristics, is prescribed in case of long-term infertility for diagnostic purposes.
Hypermacroprolactinemia
If macroprolactin is elevated, then this condition is called hypermacroprolactinemia. This pathology is not a provoking factor in the development of malignant tumors of the mammary glands and osteoporosis compared to the state of increased levels of normal prolactin.
It must be remembered that a sharp increase in the level of the hormone in non-feeding women indicates violations in the work of the hypothalamic-pituitary system. The presence of a significant amount of macroprolactin can manifest as dysmenorrhea, sometimes even causing infertility.
Prolactinoma
The term "prolactinoma" is a benign formation of the pituitary gland, a feature of which is the production of luteotropic hormone. Adenomas can occur in both women and men. The etiology of the appearance of prolactinoma has not yet been elucidated. There are opinions about hereditary predisposition, as well as that tumors appear in parallel with pathologies of other organs of the endocrine system.
Classify two types of neoplasms according to their size and localization:
- intrasellar do not extend beyond the Turkish saddle and have a diameter of less than 10 mm;
- extrasellar extend beyond the Turkish saddle and have a diameter greater than 10 mm.
In addition to the main syndromes and manifestations against which specialists prescribe diagnostics for prolactin and macroprolactin, there are a number of other clinical signs of the disease:
- narrowing of visual fields;
- a sharp decrease in visual acuity;
- double vision;
- inability to use peripheral vision;
- headache;
- depression;
- anxiety and irritability;
- in severe cases, total blindness.
In addition to laboratory diagnostics, CT and MRI of the brain, stimulation tests (hormonal) and densitometry (assessment of bone density used for differentiation) are used to make a correct diagnosis.
Diagnostic features
Analysis for macroprolactin - what is it? This is a diagnostic method of immunochemiluminescent reaction, which is prescribed to all patients with elevated levels of prolactin in the body.
Analysis is one of the innovative methods. When it is carried out, luminescent particles are “attached” to the hormone molecules, which, by binding to prolactin, illuminate areas under the action of ultraviolet radiation. The glow level is measured with luminometers - special portable devices.
Quantitative indicators of macroprolactin are determined using polyethylene glycol. They carry out the deposition of immune complexes. If after this process less than 40% of the level of totalluteotropic hormone, this is evidence that the test material contains a significant amount of macroprolactin.
Indications for diagnosis
There are a number of conditions in which experts prescribe the definition of qualitative and quantitative indicators of prolactin and its forms. Analysis for macroprolactin is carried out in the following cases:
- galactorrhea - abnormal secretion of milk or colostrum;
- the presence of prolactinomas - tumors of the adenohypophysis that synthesize an excessive amount of a hormonal substance;
- sharp deterioration of vision;
- infertility;
- absence of menstruation for more than six months;
- uterine bleeding of unknown etiology;
- study of pituitary pathology;
- regular lack of ovulation;
- osteoporosis;
- mastopathy;
- evaluation of the effectiveness of prolactin therapy.
The norm of indicators in different periods
Amount of detectable prolactin (results in µIU/ml):
- male norm - 44, 5-375;
- female norm - 59-619;
- postmenopause - 38-430;
- bearing a child - 205, 5-4420.
The results of the detection of macroprolactin are interpreted in the following ways:
- significant amount of macroprolactin;
- macroprolactin not detected;
- A significant amount of macroprolactin is in doubt.
Positive result
Hypermacroprolactinemia is determined against the background of the following pathologies:
- neoplasms of the hypothalamus;
- tumor processes of the pituitary gland;
- pathology of the thyroid gland (decrease in hormonal secretion);
- polycystic ovaries;
- kidney failure;
- liver disease;
- abnormalities of the adrenal glands, adrenal insufficiency;
- systemic lupus erythematosus;
- rheumatoid-type arthritis;
- pyridoxine hypovitaminosis.
The significant presence of macroprolactin also means that the patient may have taken medication for a long time.
Hormonal levels are affected by:
- antihistamines;
- neuroleptics;
- diuretic;
- antihypertensives;
- antipsychotic drugs;
- oral contraceptives;
- antidepressants;
- antiemetic in large quantities and with prolonged use.
Reduce values
In some conditions, macroprolactin, the norm in women of which varies depending on the period of life, may be below optimal levels. This result is typical for the following cases:
- pituitary infarction occurring against the background of massive blood loss during childbirth;
- pregnancy prolongation (more than 41-42 weeks);
- long-term use of anti-seizure drugs, Calcitonin, hormones, Morphine, Rifampicin, Nifedipine.
Who appoints the study and where to take it
Onthe study can be directed by several narrow specialists: a gynecologist, urologist or endocrinologist. The analysis is taken in the laboratories of specialized medical clinics or family planning centers. Venous blood is needed for diagnosis.
For the results to be correct, the patient needs to prepare for the test for macroprolactin:
- Refuse food 12 hours before delivery.
- Do not use estrogen and androgen-based drugs for a few days before taking. The specialist who gave the referral must inform the patient of this.
- Within 24 hours, completely stop taking medications.
- For a few days before the analysis, exclude any physical activity and avoid stressful situations.
- You must stop smoking on the day of the test.
Conclusion
One form of luteotropic hormone is macroprolactin. What is it, what are the features of checking its qualitative and quantitative indicators - the necessary information for every couple who wants to become parents in the future or is in the process of planning conception.
