B hCG what. Free beta-hCG: characteristics of the hormone, norm and deviation. Use of drugs containing human chorionic gonadotropin

– one of the main hormones that regulate the functions of the sex glands. It performs a number of important tasks in the body of a pregnant woman, helping to maintain the desired concentration of other hormones and survive the stress that pregnancy represents.

Given the important role of human chorionic gonadotropin, it is not surprising that analysis of its concentration in the blood is one of the main ones in monitoring pregnancy. The units of measurement for hCG in test results from several different laboratories may differ, so it is important to know the relationship between them to correctly interpret the results.

Why is HCG so important?

To understand why the content of human chorionic gonadotropin is one of the main markers healthy pregnancy(especially in the first trimester), it is necessary to understand its properties and effects on the body.

Along with other gonadotropic hormones (luteinizing and follicle-stimulating), as well as thyrotropin (TSH), hCG consists of an α- and β-subunit. The structure of the β-subunit of hCG distinguishes it from the listed hormones (the α-subunit is homologous to the similar structural component in FSH and TSH). During pregnancy, it is a determining factor that allows you to determine the concentration of this particular hormone due to a specific reaction to the subunit.

In its properties, hCG is reminiscent of both other gonadotropic hormones. However, despite the ability to bind to both types of receptors, luteinizing properties significantly prevail over follicle stimulation. In this capacity, hCG is significantly superior to the usual pituitary luteinizing hormone: it is thanks to its high activity that the corpus luteum, which normally exists two last weeks menstrual cycle, persists until the placenta has developed enough to produce estrogen and progesterone.

Under the influence of human chorionic gonadotropin, the corpus luteum produces a lot of hormones, which is required for the normal course of pregnancy. HCG also stimulates the production of estrogens, without which the activation of progesterone, weak androgens and glucocorticoids is impossible, which reduce the immune response to a half-foreign body and avoid miscarriage.

The role of hCG in the body of a pregnant woman explains the dynamics of hormone production: up to 10-12 weeks, its amount steadily increases, because For normal gestation, more and more progesterone is required. After the placenta matures and the tissues begin to secrete all the hormones necessary for pregnancy, the need for the existence of the corpus luteum and its intense stimulation disappears, so the concentration of hCG decreases.

Considering all of the above, an excess or deficiency of human chorionic gonadotropin in pregnant women indicates pathologies or diagnostic errors (more likely early stages gestation).

Normal concentration of human chorionic gonadotropin during pregnancy

Human chorionic gonadotropin is considered a placental hormone, despite the fact that in the absence of pregnancy, a small amount of it (not higher than 5 mIU / ml, according to some reports - up to 6.15) is produced by the pituitary gland. During pregnancy, the beta hCG rate is several orders of magnitude higher than this figure.

Normal levels of hCG in the blood by week of pregnancy;

Normally, after the corpus luteum ceases functioning, the concentration of human chorionic gonadotropin gradually decreases, but in the third trimester of pregnancy a repeated, less intense peak in the hormone level may be observed.

Previously, in medical practice, this phenomenon was considered one of the normal variants. Today, experts are more wary of the peak: an increase hCG level after the 11th week, it often indicates pathologies that threaten the health of the mother (trophoblastic disease), or placental insufficiency. The latter is often observed in cases of Rh conflict between the pregnant woman and the fetus.

To monitor the health of the fetus, as well as to determine the presence of certain types of cancer, an analysis of the content of free β-hCG is used.

The concentration of free hCG may be reported in nanograms per milliliter. The ratio of honey and mME to ng is given below.

In men and in women who are not pregnant, the level of unbound beta subunit of gonadotropin does not exceed 43 mIU/ml (maximum level of free hCG 2 ng/ml).

The table provided is indicative only. The results should be interpreted by the observing physician, because These standards are averages and may not be suitable for a particular pregnant woman due to special circumstances (some chronic diseases, multiple births, etc.).

Causes of low and high hCG levels

Possible reasons Increased hCG levels in expectant mothers can result in:

• multiple pregnancy (hormone concentration level is proportional to quantity);
• gestosis;
• severe early toxicosis;
• diabetes mellitus in a pregnant woman;
• prolonged gestation;
• discrepancy between the estimated and actual stages of pregnancy;
• taking hCG drugs or gestagens;
• chromosomal pathologies in the fetus.

U non-pregnant women increased level HCG in the blood can be associated with the onset of menopause (the normal value increases to 9.5 mIU/ml), testing less than 5 days after an abortion, and trophoblastic diseases (hydatidiform mole, etc.).

Normally, after the birth of a child, human chorionic gonadotropin is not detected in the urine, and its concentration in the blood quickly drops to normal values ​​(0-6.15 mIU/ml). If this does not happen even after 42 days after birth, gynecologists talk about trophoblastic pathology.

The cause of an increase in gonadotropin levels can also be the presence of a cancerous tumor in the intestines, kidneys, or lungs. In men, an increased amount of hCG in the blood can also be associated with seminoma and testicular teratoma, in women - with a hormone-producing neoplasm in the uterus.

A low hCG level, unlike an elevated one, is only dangerous. Possible causes of the phenomenon may be:

• ectopic location of the fetus;
• delayed fetal development;
• true post-maturity;
• risk of miscarriage;
• antenatal fetal death (with monitoring in the 2-3 trimester of pregnancy);
• chronic placental insufficiency (for example, due to Rh conflict between mother and fetus).

Not only the result is of great importance, but also the dynamics of hCG growth. For example, when it doubles on average 2 times a week, whereas normally the concentration of gonadotropin doubles every 2 days. When there is a threat of miscarriage, the hCG level rapidly decreases (on average by more than 50% of the normal value).

Features of analysis for hCG levels

Units

The concentration of chorionic hormone is measured in mIU/ml (international milliunits per milliliter), honey/ml or in mass units - nanograms per milliliter of biomaterial. The indicators honey and mME are equivalent to each other. To convert ng/ml to conventional units, you need to multiply the result by 21.28.

Thus, 21.28 mIU/ml = 21.28 mIU/ml = 1 ng/ml.

Confirmation of the result

With an hCG level of approximately 500 mIU/ml, the fetus can be detected on transvaginal ultrasound. Early ultrasound diagnostics used to clarify the location of the fetus, because the concentration of placental gonadotropin also increases with ectopic pregnancy.

Biomaterial

Blood and urine can be used to study the level of hCG concentration. Home test strips and inkjet testers are less accurate than venous blood tests, but are cheap and easy to use. The sensitivity of the tests is indicated on the packaging.

Most of them show a positive result when the hCG concentration exceeds 25 mIU/ml, i.e. approximately 2 weeks after conception. More expensive tests can indicate pregnancy earlier - already 7-10 days after fertilization of the egg.

However, in the early stages, experts advise resorting to a blood test, because it will be possible to talk about a truly positive or negative result only after several days have passed after the delay.

Use in combination with other studies

An increased level of hCG in pregnant women may indicate chromosomal diseases of the fetus (most likely Down syndrome). To clarify the result, a comprehensive screening is carried out. In the first trimester, it includes the analysis of free β-hCG and PAPP-A (pregnancy-associated plasma protein A). Low protein levels indicate a high risk of severe chromosomal pathologies. In the second trimester, screening includes the study of three biochemical markers (hCG, alphafetoprotein and estriol-A).

In the absence of pregnancy, the hCG test can be used in combination with tests for tumor markers to determine cancer.

How to get an accurate result

The correctness of the result largely depends not only on the reagents and the correct work of the laboratory staff, but also on the preparation of the patient for the study. There are several rules that will minimize the error:

• Venous blood analysis should be carried out strictly, if possible before 10 am;
• on the eve of the study, it is undesirable to eat fatty foods, drink alcohol and play sports;
• within 2-3 hours before blood sampling, you must not smoke or even drink water, and also avoid stress;
• the patient or patient must warn the laboratory technician about all medications taken, especially hormonal ones;
• It is not advisable to donate biomaterial after radiography, ultrasound, massage, physiotherapy and examinations.

This is important: for monitoring pregnancy, the dynamics of the increase in hCG levels is very important, so tests must be taken at the same time of day, under constant nutritional conditions.

Among the list of tests that a woman must undergo during pregnancy or just planning to become a mother, you can find the abbreviation “hCG”, but what is it? This analysis shows the amount of human chorionic gonadotropin, let’s look at it in more detail.

HCG, what is it?

HCG is a hormone of protein nature and consisting of two fractions - alpha and beta. The beta fraction of the hormone is of clinical interest, since alpha is similar in structure to other female hormones. And beta is unique - this makes it easy to detect in the blood.

The biological role of hCG in the body of a pregnant woman:

1. The hCG hormone contributes to the preservation of the corpus luteum during pregnancy and its production of progesterone until the placenta begins to function fully. This helps maintain pregnancy and pregnancy healthy child. Without a sufficient amount of the hormone, motherhood will not take place. The placenta begins to synthesize female hormones on its own from about 16 weeks.

2. Human chorionic gonadotropin helps a woman get used to the onset of pregnancy by stimulating the adrenal glands to produce glucocorticoids, making the expectant mother more resistant to stress. Carrying a child is stressful for the female body, especially in the early stages.

3. When the placenta has already formed (at 16 weeks), hCG ensures adequate nutrition and development, preventing premature detachment.

4. In medicine, the administration of the hormone by injection is practiced. This stimulates ovulation and promotes conception in women. By using such injections in men, it is possible to increase the level of sex hormones and improve sperm quality.

Norms of hCG levels in women

Taking a test for hCG levels is not difficult: it is simply taking blood from a vein. The analysis result is usually issued on the same day or the next.

Decoding the result of the hCG analysis performed lies on the shoulders of the doctor. It is difficult to understand the abundance of numbers and meanings on your own. However, you should remember how hormone levels change depending on the duration of pregnancy and know the average values ​​​​for non-pregnant women (see table).

Important! Normal values ​​may vary depending on the laboratory that performed the analysis.

In girls and men, hCG levels should be 0–5 mU/ml. This amount is so small that a test performed to determine hCG in urine does not react to it and will show one line.

From the first days of pregnancy, the level of hCG will increase. This happens until 11–12 weeks, when the highest hormone levels are noted. Next, gonadotropin gradually decreases and in the last stages of pregnancy shows approximately the same value.

Increased hCG during pregnancy

With the onset of fertilization, the level of human chorionic gonadotropin increases. This happens literally immediately after fertilization.

The quantitative composition of the hormone grows steadily and reaches a maximum by week 11, and then declines. In the second half of pregnancy, the indicators stabilize and change little.

Express tests sold in pharmacies to determine pregnancy can change color when hCG is in the urine. Although the method is not as revealing as a blood test for hCG, it is still quite accurate. In a non-pregnant woman, the result will be negative, while a pregnant woman will be able to find out about the presence of pregnancy before other signs appear.

A blood test for human chorionic gonadotropin can give an answer within 7-10 days from the moment the egg and sperm meet. Obtaining the results of an hCG analysis at such an early stage makes it possible to control the course of pregnancy almost from the very moment of fertilization.

Careful monitoring of the level of the most important hormone of pregnancy will prevent complications of pregnancy, including its termination. This is true for women who have unsuccessfully tried to experience the joy of motherhood, as well as for late-birthers or women with a burdened obstetric history.

If the level of hCG in a woman “in an interesting position” exceeds the norm, then this may be evidence of the following processes in the body:

1. When carrying two or three fruits.
2. Diseases of the fetus at the chromosomal level (Down syndrome).
3. History of diabetes mellitus in pregnancy.
4. Severe course of gestosis during pregnancy.
5. External use of female hormones.

Decrease in hCG during pregnancy

Gonadotropin levels may decrease in the following cases:

1. With an atypical location of the ovum (tubal, or).
2. If the fetus lags behind in its development.
3. During a frozen pregnancy.
4. If there is a violation of blood circulation between the baby and the placenta or between the placenta and the uterus.
5. If .
6. When postterm.

Increased hCG in women and men

A blood test for the hCG hormone in a non-pregnant woman or in men provides important diagnostic information. There have been cases where men, as a joke, took a pregnancy test and received two stripes.

On the one hand, this seems absurd and impossible, but on the other hand, this is no reason for jokes. Human chorionic gonadotropin can appear in the body of men and women during the development of a malignant tumor.

These are so-called hormone-producing tumors that can form in the organs of the reproductive system, lungs, and stomach.

Explanation of hCG analysis, table

For a doctor, decoding the result of an hCG test carries a lot of information during pregnancy. By analyzing blood parameters for the quantitative content of the hormone, the doctor will accurately determine the duration of pregnancy, and will also be able to suspect an ectopic pregnancy, some pathologies, an impending miscarriage, etc.

This will help take measures to preserve the desired child and take actions aimed at preventing complications in the expectant mother and her baby.

Of course, a diagnosis cannot be made based solely on the level of this hormone. More research is needed. But it is the amount of the main hormone of motherhood that indicates possible problem and sends the doctor to in the right direction to identify this problem.

The results of an hCG analysis done in the laboratory can be indicated in different units of measurement: honey/ml, U/lm, IU/ml, mIU/ml - these are the same thing. remember, that The results in each laboratory may vary slightly!

With the onset of pregnancy, the expectant mother will have to undergo a lot of research and undergo many tests. Most often, women are prescribed a general examination of urine and blood. However, the results of such diagnostics cannot confirm or refute the new interesting situation. This article will focus on beta-hCG. You will find out what this substance is and why it is formed. It is also worth mentioning at what time you need to take a beta-hCG test. In medicine, there are generally accepted norms for this substance in a woman’s blood in different periods pregnancy.

Beta HCG

This substance is secreted by the fertilized egg and placenta. It appears in the blood of the expectant mother the very next day after implantation. At the same time, conventional pregnancy tests still show negative result. This is due to the fact that the amount of beta-hCG in the urine is much less than in the blood. That is why, if you want to quickly find out about your pregnancy, you should take a blood test.

During the period from the thirteenth to the eighteenth week, a range of this hormone can be observed in the blood of the expectant mother ranging from 6140 to 103,000 units. After this (up to approximately the 24th week of embryonic development), the level of human chorionic gonadotropin is 4720-80 100 IU/ml.

Third trimester

At this stage, hormone levels are very rarely measured. However, there are generally accepted standards that are oriented towards when it is necessary to conduct research. So, in the period from the 23rd to the 40th week, 2700-78,100 units of the substance are found in the blood of the expectant mother.

Remember that when multiple pregnancy the amount of human chorionic gonadotropin may be slightly higher.

Possible pathologies

Is there a certain norm for beta-hCG for possible pathologies? Unfortunately, medicine has not yet established certain data. All due to the fact that the pathology can begin at different dates and at different conditions. Also, the body of each expectant mother is individual and cannot react to possible difficulties in the same way.

• When the hormone level reaches its norm before a certain week (usually the 5th-6th). After this, a sharp decline in the substance occurs, and the analysis shows negative values.
• An ectopic pregnancy is characterized by the fact that the norm of beta-hCG is not achieved. The hormone level is growing, but very slowly and significantly lags behind the established values.
• HCG levels are much higher than normal during hydatidiform mole. However, during an ultrasound, an embryo with a heartbeat is not detected.
• If the expectant mother suffers from diabetes, then the amount of beta-hCG may also exceed normal values.

Can a normal pregnancy not meet the established hCG standards?

It also happens that the fetus develops absolutely normally, but the amount of human chorionic gonadotropin in the woman’s blood is significantly higher or lower than normal. Why is this happening?

Most often, this situation arises in the very early stages. At the same time, the woman cannot accurately name the date of conception. If the gestational age is set incorrectly, then the hormone levels may diverge from the established standards. Most often, ultrasound diagnostics helps clarify the situation. During an ultrasound, the doctor can accurately determine the duration of pregnancy (up to one day).

Summing up and concluding the article

So, you now know what levels of human chorionic gonadotropin are allowed during pregnancy. Remember not to rely too much on established numbers. Each woman's body is individual and can react differently to a new position. Do not take into account the numbers that your friends had at one time or another. Some doctors say that the normal level of beta-hCG may vary depending on the gender of the unborn child.

If you get a bad result, you should repeat the analysis. Often there is a laboratory error or incorrect comparison with standards. When decoding data, always pay attention to the established study center values. They may be very different from other laboratories. Also, the result can be displayed in different units of measurement. All this greatly influences the obtained values. To clarify the situation, contact your gynecologist and follow all instructions given. Have an easy pregnancy!

General information about the study

Human chorionic gonadotropin (hCG) is a hormone that is produced in the membranes of the human embryo. It is an important indicator of the development of pregnancy and its deviations. It is produced by the cells of the chorion (the membrane of the embryo) immediately after its attachment to the wall of the uterus (this happens only a few days after fertilization). The embryo at this stage of pregnancy is a microscopic bubble filled with liquid, the walls of which consist of rapidly multiplying cells. From one part of these cells it develops unborn child(embryoblast), while from the cells located outside the embryo, a trophoblast is formed - that part of the fertilized egg with which it attaches to the wall of the uterus. Subsequently, the chorion is formed from the trophoblast.

The chorion performs the function of feeding the embryo, being an intermediary between the body of the mother and the child. In addition, it produces chorionic gonadotropin, which, on the one hand, affects the formation of the child, and on the other, has a specific effect on the mother’s body, ensuring a successful pregnancy. The appearance of this hormone in the body of the expectant mother initial stage pregnancy and explains the importance of the test for early diagnosis pregnancy.

Human chorionic gonadotropin stimulates the secretory function of the corpus luteum of the ovaries, which should produce the hormone progesterone, which maintains the normal state of the inner lining of the uterine wall - the endometrium. The endometrium ensures reliable attachment of the fertilized egg to the mother’s body and supplies it with all the necessary substances.

Thanks to sufficient amounts of human chorionic gonadotropin, the corpus luteum, which normally exists for only about 2 weeks during each menstrual cycle, with successful conception does not undergo resorption and remains functionally active throughout the entire pregnancy. Moreover, it is precisely in pregnant women that, under the influence of human chorionic gonadotropin, it produces very large amounts of progesterone. In addition, hCG stimulates the production of estrogens and weak androgens by ovarian cells and promotes the development functional activity the chorion itself, and subsequently the placenta, which is formed as a result of the maturation and growth of chorionic tissue, improving its own nutrition and increasing the number of chorionic villi.

Thus, the role of human chorionic gonadotropin is to have a specific and multifaceted effect on the body of the woman and the fetus in order to ensure a successful pregnancy. Based on an analysis for human chorionic gonadotropin, the presence of chorionic tissue in a woman’s body is determined, and hence pregnancy.

By chemical structure human chorionic gonadotropin is a compound of protein and complex carbohydrates, consisting of two parts (subunits): alpha and beta. The alpha subunit of human chorionic gonadotropin is completely identical to the alpha subunits of luteinizing, follicle-stimulating and thyroid-stimulating hormones of the pituitary gland, which perform functions largely similar to the function of human chorionic gonadotropin, but not during pregnancy. The beta subunit of human chorionic gonadotropin is unique, which, on the one hand, determines the specificity of its action, and on the other, allows it to be identified in biological environments. Due to this this test is called the beta subunit of human chorionic gonadotropin (beta-hCG).

Knowing the level of beta-hCG in the blood, it is possible to diagnose pregnancy already on the 6-8th day after conception (in the urine the concentration of beta-hCG reaches the diagnostic level 1-2 days later). Normally, during pregnancy, between the 2nd and 5th week, the amount of beta-hCG doubles every 1.5 days. In multiple pregnancies, it increases in proportion to the number of fetuses. The hCG level reaches its maximum in the 10-11th week, and then gradually decreases. This occurs due to the fact that from the beginning of the 2nd third of pregnancy, the placenta is able to independently produce enough estrogens and progesterone, with the participation of which the endometrium functions normally regardless of the secretion of hormones in the corpus luteum of the ovaries. At the same time, the concentration of hCG in the blood of a pregnant woman gradually decreases, and the corpus luteum can function without the influence of hCG. During this period, the role of the hormone is to stimulate the production of testosterone in the fetus, which is necessary for normal development external genitalia of the embryo.

Thus, during pregnancy, the level of beta-hCG in the blood first increases and then decreases. Using this indicator, one can judge the successful course of pregnancy and identify fetal development disorders. A test for hCG in the blood is the most reliable method for determining pregnancy in the early stages. HCG appears in a woman’s body from 6-8 days after fertilization. A common rapid pregnancy test, which every woman can use at home, is also based on measuring hCG in the urine.

Hormone levels below normal at various stages of fetal development suggest an ectopic pregnancy, delay in fetal development, threat of spontaneous abortion, non-developing pregnancy or placental dysfunction. The cause of increased levels of beta-hCG may be toxicosis, diabetes mellitus, or an incorrectly determined gestational age. A high level of the hormone after a mini-abortion indicates a progressive pregnancy.

Determination of the level of hCG is included in a triple test study, the results of which can be used to judge some abnormalities of fetal development, but an accurate diagnosis cannot be made. The study only allows us to classify a woman as a risk group for this pathology. In this case, further examination is necessary. In non-pregnant women, hCG is normally absent, but it can be secreted by some abnormal tissues originating from the chorion (hydatidiform mole, chorionepithelioma) and some other tumors.

What is the research used for?

• For diagnosing pregnancy, including multiple pregnancy, ectopic and non-developing.
• To monitor the progress of pregnancy.
• To identify delays in fetal development, threat of spontaneous abortion, insufficiency of placental function.
• For the diagnosis of amenorrhea.
• To monitor the effectiveness of induced abortion.
• As part of a comprehensive examination to identify fetal malformations.
• For the diagnosis of tumors producing hCG.

When is the study scheduled?

• If you suspect a pregnancy, in particular multiple pregnancy.
• When monitoring the progress of pregnancy.
• When there is an assumption of a complication during pregnancy: delayed fetal development, threat of spontaneous abortion, non-developing or ectopic pregnancy, chronic failure functions of the placenta.
• If necessary, confirm the successful completion of an induced abortion.
• During a comprehensive examination to identify fetal malformations.
• When determining the cause of the absence of menstruation (amenorrhea).
• When is the diagnosis of hCG-producing tumors carried out?