HCG or hCG is human chorionic gonadotropin. This is the name of the hormone, the presence of which in the body of a woman of fertile age will indicate her pregnancy. It appears in the blood from the cells of the chorion of an already functioning embryo. These cells form the membrane of an embryo attached to the wall of the uterus.
If there is a sufficient amount of this hormone in the blood, pregnancy has come. But it can also be detected in a non-pregnant woman or even in a man. In the case of its increased indicators, a survey is required, as this indicates a pathology. Chorionic gonadotropin is very sensitive, but non-specific. In other words, it can increase with a number of diseases, usually with neoplasms.
HCG during pregnancy
Features of the production of hCG during gestation:
- It begins to stand out quite soon - it can be found in the blood of a woman, from the moment of conception in just a week.
- It has the effect of sex hormones and immediately begins to stimulate the growth of the fetal membranes. It increases and grows in the first trimester, because it is during this period that the laying and intensive development of the most important organs of a small person occurs.
- The hCG level, rising to 12 weeks, then freezes at a certain level for a while. Later, its gradual decline begins towards the end of pregnancy and the onset of childbirth.
- The presence of hCG in the blood and its excretion in the urine is based on the definition of pregnancy by the biochemical reaction of the stripes. The analysis is only qualitative, he does not give figures.
Why do you need to know hCG in pregnant women
This is necessary to obtain information about the course of pregnancy in a woman and her health. The most important function of the hormone is to ensure the normal course of pregnancy. With certain values, he will indicate to the doctor a multiple pregnancy.
Thanks to him, the carrying of the baby proceeds normally, and the fetus is not rejected by the mother's body. HCG stimulates the formation of the right amount of progesterone and estrogen in the body. The corpus luteum works due to the support of hCG, and it also activates the ovulation process.
Corpus luteum and chorionic gonadotropin
Without fertilization of the egg, monthly involution of the corpus luteum occurs in phase 2 of the MC after ovulation. It is physiological. But if conception occurred and the embryo began to produce hCG, the corpus luteum continues to live and work. Its main function is the production of progesterone in large quantities, since it is also considered a hormone of pregnancy and ensures its phased course.
The implantation of the zygote into the endometrium not only occurs completely, but also ensures the further adequate development of the fetus. HCG also stimulates the synthesis of sex steroids by the ovaries. This enhances the activity of chorionic villi at the site of the future placenta, which is important for trophic fetus.
After the formation of the placenta, the role of hCG is to activate the production of testosterone, but not in the mother, but in the fetus. This ensures the development of the reproductive system of the developing embryo. So, hCG free during pregnancy is its main regulator.
HCG hormone structure
There is a concept of common hormone and free. Total hCG consists of 2 components: alpha and beta component subunits.
The alpha component is the entire set of pituitary hormones (TSH, FSH and LH). Accordingly, thyroid-stimulating, follicle-stimulating and luteinizing hormones.
What does it mean - the free beta subunit of hCG? When talking about hCG, it means the beta component. Thanks to her, you can find out about the presence of pregnancy.
Free hCG is not associated with proteins and it is he who has specificity. Based on it, pregnancy test strips are compiled.
The difference between beta-hCG and the alpha unit is its uniqueness. This component is a protein and contains 145 amino acids. In total, bound and free hCG give a total hormone.
Beta-hCG is the most reliable diagnosis of pregnancy from an early stage of embryo life. And although it can be detected in the blood from the 8th day of fertilization, doctors suggest the possibility of such an analysis immediately after the delay of menstruation. Already then the hormone begins to grow.
Diagnosis of pregnancy by the testimony of hCG
To determine pregnancy, 2 methods are used:
- Strip tests and hCG blood tests. Tests are convenient, cheap and affordable. But not always reliable. The fact is that in urine the amount of hCG is lower than in blood by 2 times. It can also be carried out with a delay of 2 days.
- More accurate is the study of venous blood for the presence of hCG. Preparation and conduct are standard. If delivery in the morning on an empty stomach turned out to be unfulfilled, another option is after eating after 4 hours.
A convenient period is considered after the proposed conception. Confirmation of pregnancy can be considered the content of hCG above 25 mU / ml. A level below 5 mU / ml will indicate the absence of pregnancy.
If you suspect the analysis is repeated three times every 3 days. With stable dynamics, an interesting position is confirmed.
Norm and units
The rate of free hCG beta beta subunit in the blood throughout the gestation period is expressed in the following units:
- mU / ml (milli-units);
- mIU / ml (milli-international units);
- 1 mU / ml = 1 mmU / ml.
Sometimes the laboratory gives the result in international units, which is generally similar to the above, ng / ml (nanograms per milliliter), etc. The norm of free hCG beta subunit in laboratories of medical institutions can vary. The discrepancy is explained by different methods, equipment. The optimal solution is to take tests in one laboratory. Tracking the dynamics of the content of changes in hCG in the blood will become more reliable.
Sometimes there is honey / l. To obtain the norm of the free beta subunit of hCG in mU / l, 1 ng / ml x 21.28 = 1 mU / l.
HCG changes in gestational age
The growth rate of the indicated hCG fraction proceeds at different rates throughout the entire gestation period. Typically, gynecologists observe an increased free beta subunit of hCG in the blood of the expectant mother until a certain period - an increase in the hormone in the first 10 weeks twice every 2 days. This is subject to a normal course of gestation.
What is the norm for the free beta subunit of hCG at different periods of gestation? In the first trimester, from 3 to 4 weeks, from 16 to 156 units will be in the woman’s blood plasma. Further, up to 5 weeks, no more than 4870 IU / ml is released. Until approximately a 6-week period, the hCG level doubles every 2 days.
Further, up to 8 weeks, doubling slows down a little - every 3 days. Further, the level of units is on the decline.
At week 5 and 6, the amount of the hormone is from 1110 to 31500 units. At a period of 6-7 weeks, a range of 2560-82 300 IU / ml can be detected.
At 7-8 weeks, the hormone ranges from 2310 to 151,000 units / ml. At week 9, 20000-100000 mU / ml. 10-11 weeks maximum - 291,000 units.
The norm of free hCG beta subunit at 12 weeks does not exceed 30,000 IU / ml. This period is considered the boundary between the first and second trimester.
This is the norm of free hCG beta subunit at 12 weeks. During this period, a woman's hormone production decreases and for some time its level does not increase.
Transition to the 2nd trimester
So, the second trimester. At this stage, the level of free beta-subunit of hCG during pregnancy begins to decline. But with double it can remain the same or even rise slightly, which doctors consider the norm.
The norm of free hCG beta subunit from 13 to 18 weeks will be from 6,140 to 103,000 units. In the future, up to 24 weeks, the hCG bar is 80 thousand IU / ml.
Final 3 trimester
Here, the measurement of the level of the hormone is very rare, because it is impractical. But generally accepted norms exist here. And the reader has the opportunity to familiarize themselves with them.
From the 23rd to the 40th week should not be higher than 2700-78100 IU / ml. Overestimated rates are characteristic for multiple pregnancy. Specifically, the 40th week of pregnancy has indicators of 60,000-70000 units - this is the norm of free hCG beta subunit in this case.
With deviations from these figures, the doctor may suspect the following violations of the current pregnancy:
- the possibility of a miscarriage;
- missed pregnancy;
- ectopic pregnancy;
- hormone deficiency in the placenta.
Other enhancement factors
An increased level of hCG is not the norm and may indicate:
- carrying twins or triplets;
- post-term pregnancy (longer than 42 weeks);
- incorrect gestational age;
- the phenomenon of early or severe toxicosis;
- the presence of diabetes in a pregnant woman;
- treatment of women with synthetic gestagens;
- fetal genetic disease (Down syndrome comes with an hCG of 500,000 IU / L).
Causes of a low hCG in a future mother
The transition of hCG beyond the normal line downward during gestation - this also requires a serious attitude, since it indicates a pathology of pregnancy or a chronic disease in the woman herself.
These reasons include:
- ectopic pregnancy;
- frozen gestation or fetal death in the womb;
- chronic hormone deficiency in the placenta;
- pregnancy overtaking; the threat of miscarriage (in this case, hCG drops immediately 2 times).
All possible pathologies should be checked as soon as possible to avoid complications.
If the norm of the free beta subunit of hCG is lower than the norm, it is likely that bearing a further pregnancy will be impossible or risky. If hCG is low with late prenatal screening in a pregnant woman, growth retardation or development of a future man may be suspected.
HCG in non-pregnant women
There are cases when the free beta subunit of hCG is elevated in the absence of pregnancy or even in a man. This is always not the norm. Reference values are considered normal, regardless of gender - 0-2 ng / ml.
The occurrence and increase of this substance in blood plasma in the absence of pregnancy above the specified value will talk about:
- cystic drift or hormone-dependent tumor in a woman;
- an abortion performed about 5 days ago;
- taking progestogens;
- relapse of cancer after irradiation;
- testicular tumors in men;
- neoplasms in the intestines;
- cancer of the kidneys and lungs;
- malignant tumors in the uterus.
In the case of malignant tumors, the level of the hCG free beta subunit hormone above normal in the blood can be used as a tumor marker when there are no clinical symptoms in the next few months. With a successful surgical intervention in such patients, the level of the hormone normalizes in 2-3 days. Otherwise, the numbers indicate damage to other organs and systems or poor-quality treatment.
Possible pathologies
Is it possible to put a pathology on the basis of hCG figures? Accurate data on this subject has not been identified. The problem is that the body of each woman is individual, and pathology can occur under different conditions and at different times.
There cannot be a common denominator here. Each organism has its own octave of response to difficulties. For example, with biochemical pregnancy at 5-6 weeks, there is already a hCG norm. This name has a non-developing pregnancy or spontaneous miscarriage. But then a catastrophe ensues - it drops sharply to negative values.
With an ectopic pregnancy, the hCG norm is not achieved. The hormone level rises so slowly that it constantly lags behind its norms.
The values of the hCG level are off scale with cystic drift or its relapse. An ultrasound may give a hint, on which the fetus with a heartbeat will not be detected. Also, hormone levels increase with diabetes in a pregnant woman.
What is MoM
The standard units of measure for free hCG are MED / ml, but MoM is more commonly used in the laboratory today. Its numerical expression does not exceed 2. A table indicating MoM with the gestational age is available for all gynecologists.
Any laboratory result you get is simply multiplied by the median value. This is very convenient for the doctor when they bring results from different laboratories.
So what is MoM? The abbreviation MoM comes from English multipleofmedian, which means “multiple of the median”. Gynecologists call the median the average value of an indicator at any stage of pregnancy. Since the body of each person is individual, and the standards of the laboratories are standard, there is confusion when trying to fit everyone into one line.
The error in this case is undeniable and quite high. Therefore, MoM was created - a coefficient by which you can find out the degree of deviation of a particular result from the median.
The median is the middle. The middle is the optimum, and the leap up and down is bad. MoM does not have its own unit of measurement; it is calculated in the same system as the indicator itself.
What factors can affect MoM?
MoM can be affected by a woman’s weight, diabetes, pregnancy as a result of IVF, and some drugs taken by a woman. The norm of MoM of the free hCG beta subunit ranges from 0.5 to 2.5. And with double-triple up to 3.5 MoM.
According to the results obtained, the doctor can always determine whether his ward is among the women with possible chromosomal pathologies in the fetus or not already at the screening stage.