Prolactin (luteotropic) is a hormone produced by adenohypophysis cells. The substance has several forms in the form of which it is in the human body. One of these forms of luteotropic hormone is macroprolactin. What is it, what are its functions and properties, we will consider further.
Basic concepts of 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 the action are the mammary glands.
Prolactin-responsive receptors have been found in other parts of the body, but it is still unclear how they respond to the influence of hormonal substances. Sensitive receptors are found in the following organs:
- spleen;
- lungs;
- thymus
- heart;
- pancreas;
- kidneys
- uterus and ovaries;
- skin integument.
The hormone exists in human blood in three forms: 85% of the substance has the form of a monomer, 10% - the form of a dimer, and only 5% are in the form of macroprolactin.
Prolactin Functions
The main "task" of the hormone is to increase and maintain a sufficient level of milk formation during lactation. During pregnancy, a sufficient level of prolactin is supported by the sex hormones estrogen. After the birth of the baby, the amount of estrogen decreases sharply.
During this period, prolactin production is supported by stimulation of the nipple mechanoreceptors. The baby with his active breast sucking 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 isolation.
The action of prolactin during pregnancy can be visually seen on a newborn. The high hormone content leaves an imprint on the baby. A few days after birth, there may also be milk secretions from the baby’s breast that do not require additional intervention and pass independently during the first week of life.
Other properties of luteotropic hormone:
- inhibition of ovulation;
- lengthening the period of existence of the corpus luteum;
- preventing new pregnancy;
- low analgesic effect;
- participation in the formation of surfactant;
- ensuring immune tolerance of the embryo;
- participation in providing an orgasm.
The mechanism of development of pathology
In the body of a healthy man and a non-pregnant woman who does not have health problems, the production of prolactin is inhibited by the active substance dopamine. It is synthesized in the hypothalamus. Under any pathological conditions, the relationship between the pituitary and hypothalamus is disturbed, as a result of which the cells of the adenohypophysis synthesize luteotropic hormone and its level in the blood serum increases.
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 immunoglobulin.
Prolactin and macroprolactin in an amount above the norm should be present only in the body of a pregnant and lactating woman. All other cases are considered pathological.
Macroprolactin having a higher molecular weight tends to accumulate in the body. Other forms of luteotropic hormone are excreted faster due to low molecular weight indicators.
Macroprolactin, the norm of which will be discussed below, has low biological activity, which means that the body may not react in any way to minor changes in its parameters. The clinical picture is poorly expressed or accompanied by menstrual irregularities, which is not a specific indicator of pathology.
In males, this hormone is also synthesized. He is responsible for the production of sperm, their activity and the synthesis of testosterone. In men, macroprolactin is much lower than in women.
An analysis to study the level of the hormone, as well as its qualitative and quantitative characteristics, are prescribed in case of prolonged infertility with 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 with the state of increasing the amount of conventional prolactin.
It must be remembered that a sharp increase in the level of the hormone in non-lactating women indicates abnormalities in the functioning of the hypothalamic-pituitary system. The presence of a significant amount of macroprolactin can manifest itself in the form of dysmenorrhea, sometimes even causing infertility.
Prolactinoma
The term "prolactinoma" refers to the 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 a hereditary predisposition, as well as the fact that tumors appear in parallel with the pathologies of other organs of the endocrine system.
Two types of neoplasms are classified by their size and localization:
- intrasellar ones do not extend beyond the Turkish saddle and have a diameter of less than 10 mm;
- extrasellar spread outside the Turkish saddle and have a diameter of more 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;
- bifurcation in the eyes;
- inability to use lateral vision;
- headache;
- depression;
- anxiety and irritability;
- in severe cases, complete blindness.
In addition to laboratory diagnostics, CT and MRI of the brain, stimulation tests (hormonal) and densitometry (evaluation of bone density used for differentiation) are used to make a correct diagnosis.
Diagnostic Features
Macroprolactin analysis - what is it? This is a diagnostic method of the 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, when bound to prolactin, highlight areas under the influence of ultraviolet radiation. The level of luminosity 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 total luteotropic hormone is determined in blood serum , then this is evidence that a significant amount of macroprolactin is in the test material.
Indications for diagnosis
There are a number of conditions in which specialists prescribe the determination of qualitative and quantitative indicators of prolactin and its forms. Macroprolactin analysis is performed in the following cases:
- galactorrhea - pathological secretion of milk or colostrum;
- the presence of prolactin - adenohypophysis tumors that synthesize an excessive amount of a hormonal substance;
- sharp visual impairment;
- infertility;
- lack of menstruation for more than six months;
- uterine bleeding of unknown etiology;
- study of the pathology of the pituitary gland;
- regular lack of ovulation;
- osteoporosis;
- mastopathy
- evaluation of the effectiveness of prolactin therapy.
The norm of indicators in different periods
The amount of detectable prolactin (results in µIU / ml):
- male norm - 44.5-375;
- women's norm - 59-619;
- postmenopause - 38-430;
- bearing a child - 205.5-4420.
Macroprolactin detection results are interpreted in the following variants:
- significant amount of macroprolactin;
- no macroprolactin detected;
- significant amount of macroprolactin is in doubt.
Positive result
Hypermacroprolactinemia is determined against the background of the following pathologies:
- neoplasms of the hypothalamus;
- pituitary tumor processes;
- pathology of the thyroid gland (decrease in hormonal secretion);
- polycystic ovary;
- renal failure;
- liver disease
- abnormalities of the adrenal gland, adrenal insufficiency ;
- systemic lupus erythematosus;
- rheumatoid arthritis;
- hypovitaminosis of pyridoxine.
The significant presence of macroprolactin also means that the patient could take medications for a long time.
The hormonal level is affected by:
- antihistamines;
- antipsychotics;
- diuretics;
- antihypertensive agents;
- antipsychotic drugs;
- oral contraceptives;
- antidepressants;
- antiemetic in large quantities and with prolonged use.
Decrease in values
In some conditions, macroprolactin, the norm in women of which varies depending on the period of life, may be lower than optimal values. This result is typical for the following cases:
- pituitary infarction arising against the background of massive blood loss during childbirth;
- pregnancy extension (more than 41-42 weeks);
- prolonged use of drugs to combat seizures, Calcitonin, hormones, Morphine, Rifampicin, Nifedipine.
Who prescribes the study and where to pass it
Several narrow specialists can send for research: the gynecologist, the urologist or the endocrinologist. The analysis is passed in the laboratories of specialized medical clinics or family planning centers. For diagnosis, venous blood is required.
In order for the results to be correct, the patient needs to prepare for the test for macroprolactin:
- 12 hours before delivery, refuse food.
- A few days before taking do not use drugs based on estrogen and androgen. The specialist who gave the direction should inform the patient about this.
- For 24 hours, completely stop taking medications.
- For several days before the analysis, exclude any physical activity and avoid stressful situations.
- On the day of the test, you need to quit smoking.
Conclusion
One of the forms of luteotropic hormone is macroprolactin. What is it, what are the features of checking its qualitative and quantitative indicators - the necessary information for each couple who wants to become parents in the future or is in the process of planning conception.