Human chorionic gonadotropin (HCG+β)

Why this test?

• For prenatal screening in the first and second trimester of pregnancy in order to diagnose the risk of developing chromosomal abnormalities of the fetus
• For diagnosing and monitoring the course of trophoblast diseases
• To diagnose the risk of developing and the presence of testicular tumors
• For the diagnosis of malignant neoplasms that produce hCG To evaluate the effect of specific treatment against tumor neoplasms

In what cases is it prescribed?

• In case of suspicion of pregnancy, in particular multiple pregnancy.
• When monitoring the course of pregnancy.
• When there is an assumption of complications during pregnancy: delayed fetal development, threat of spontaneous abortion, frozen or ectopic pregnancy, chronic insufficiency of placental function.
•  If necessary, confirm a successful artificial abortion.
• During a comprehensive examination to detect defects in the development of the fetus.
• When finding out the reason for the absence of menstruation (amenorrhea).
• When the diagnosis of HCG-producing tumors is made.

Test information

Human chorionic gonadotropin (hCG) is a hormone produced in the amniotic membrane of a human embryo.

 It is an important indicator of the development of pregnancy and its abnormalities. It is produced by the cells of the chorion (embryo sheath) immediately after it is attached 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. The future child (embryoblast) develops from one part of these cells, while the trophoblast is formed from the cells outside the embryo - that part of the fetal egg, with which it is attached to the wall of the uterus. Later, a chorion is formed from the trophoblast.

 The chorion performs the function of feeding the embryo, being an intermediary between the organism 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, it affects the mother's body in a specific way, ensuring a successful pregnancy.

The appearance of this hormone in the expectant mother's body at the initial stage of pregnancy explains the importance of the test for early diagnosis of pregnancy. 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 ovum to the mother's body and its nourishment with all the necessary substances.

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

Thus, the role of HCG consists in a specific and multifaceted effect on the body of the woman and the fetus with the aim of a successful pregnancy. Based on the chorionic gonadotropin analysis, the presence of chorionic tissue in a woman's body is determined, which means pregnancy. According to its chemical structure, chorionic gonadotropin is a combination of protein and complex carbohydrates, consisting of two parts (subunits): alpha and beta.

The alpha-subunit of chorionic gonadotropin is completely identical to the alpha-subunits of luteinizing, follicle-stimulating, and thyroid-stimulating hormones of the pituitary gland, which perform functions similar in many respects to the function of hCG, but not during pregnancy. The beta subunit of chorionic gonadotropin is unique, which, on the one hand, determines the specificity of its action, and on the other hand, allows its identification in biological environments. In this regard, this test is called «beta-subunit of chorionic gonadotropin (beta-hCG)».

 Knowing the level of beta-hCG in the blood, it is possible to diagnose pregnancy on the 6-8th day after conception (the concentration of beta-hCG in the urine 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.

With multiple pregnancies, it increases proportionally to the number of fetuses. The hCG level reaches its maximum at the 10-11th week, and then gradually decreases. This happens due to the fact that from the beginning of the second trimester of pregnancy, the placenta is able to independently produce enough estrogen 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 the normal development of the embryo's external genitalia. Thus, during pregnancy, the level of beta-hCG in the blood first increases and then decreases. According to this indicator, it is possible to judge about the successful course of pregnancy and detect fetal development disorders.

The test for hCG in the blood is the most reliable method of determining pregnancy in the early stages. HCG appears in a woman's body from the 6-8th day after fertilization. A common express pregnancy test that every woman can use at home is also based on measuring hCG in urine. Levels of the hormone below the norm at various stages of fetal development allow us to make assumptions about ectopic pregnancy, delays in fetal development, the threat of spontaneous abortion, or placental insufficiency. The reason for the increased content of beta-hCG can be toxicosis, diabetes or an incorrectly set pregnancy period.

 A high level of the hormone after a mini-abortion indicates an advanced pregnancy. Determination of the hCG level is included in the triple test lying down, based on the results of which it is possible to judge about some anomalies of fetal development, but an exact diagnosis cannot be made.

 The study only makes it possible to assign a woman to the risk group for this pathology. In this case, further examination is necessary. In non-pregnant women, hCG is normally absent, but it can be produced by some abnormal tissues formed from the chorion (alveolar drifts, chorioepitheliomas) and some other tumors.