Definition

Human chorionic gonadotropin(also known as HCG) is a hormone used by the mother to recognize pregnancy and is produced by trophoblast cells around the growing embryo (originally syncytiotrophoblasts), which eventually form the placenta after implantation. The presence of HCG can be detected in some pregnancy tests (HCG pregnancy strip test). Human chorionic gonadotropin (HCG) is a chemical produced by trophoblast tissue, which is normally found in early embryos and eventually becomes part of the placenta. Measuring HCG levels can help differentiate between normal and pathological pregnancies, and may also be useful after miscarriage. Measurement of hCG in a variety of cancers, including choriocarcinoma and extrauterine malignancies, is also beneficial. Human chorionic gonadotropin is a glycoprotein composed of 237 amino acids with a molecular weight of 36.7 kDa, approximately 14.5 kDa α-HCG and 22.2 kDa β-HCG. It is a heterodimer with the same α subunits as luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), and the β subunit specific to HCG. Human chorionic gonadotropin is mainly catabolized by the liver, but about 20% is excreted in the urine. β subunits are degraded within the kidney to form core fragments, as determined by urine HCG test.

Fig. 1 Beta-HCG specific for pregnancy

Fig. 2 A typical structure of hCG α subunit and β subunit

Fig. 3 Crystal structure of HCG

Function

Serum HCG can not only detect early pregnancy and monitor normal pregnancy, but also an important means of detecting ectopic pregnancy in early pregnancy, such as endocrine diseases, hydatidiform mole, ectopic pregnancy, multiple pregnancy, tumor and so on.

--Promote the aromatization of androgens into estrogen, and stimulate progesterone formation

Human chorionic gonadotropin interacts with the LHCG receptors of the ovaries to promote the maintenance of the corpus luteum so that the mother recognizes the pregnancy in the first trimester. This allows the corpus luteum to secrete progesterone in the first trimester. Progesterone enriches the blood vessels and capillaries of the uterus, allowing it to maintain the growth of the fetus.

--Be used to clinically induce ovulation in the ovaries as well as the production of testosterone in the testes.

Before the secretion of LH by the fetal pituitary gland, it stimulates the secretion of testosterone by the fetal testis to promote male sex differentiation. It can also promote gonadal development, stimulate the vitality of testicular interstitial cells and increase the secretion of male hormones (testosterone). It is of great significance for the treatment of male with combined pituitary deficiency. It can not only promote gonadal development and secretion of male hormones, but also promote the development of secondary sexual characteristics.

--Be adsorbed on the surface of trophoblasts to prevent embryotrophoblast cells from being attacked by maternal lymphocytes

It is hypothesized that HCG may be the placental link in the development of local maternal immune tolerance. For example, hCG-treated endometrial cells induce increased T cell apoptosis (T cell lysis). These results suggest that HCG may be a link in the development of immune tolerance in trophoblast cells and may promote invasion of the trophoblast, which is known to accelerate fetal development in the endometrium. It has also been suggested that hCG levels are related to the severity of morning sickness or pregnancy vomiting in pregnant women.

Fig. 4 F-β-HCG test

The ability to quantify β-hCG levels can be used to monitor germline and trophoblast tumors, follow-up after abortion, and follow-up after treatment of ectopic pregnancy. The absence of a visible fetus on vaginal ultrasound after β-hCG levels of 1500 mIU/mL strongly suggests an ectopic pregnancy. Gestational trophoblastic disorders, such as molar pregnancy ("molar pregnancy") or choriocarcinoma, may produce high levels of β-hCG (due to the presence of syncytial trophoblast – part of the villi that make up the placenta) despite the absence of an embryo.

Human chorionic gonadotropin can be used as a tumor marker because its β subunit is secreted by a number of cancers, including seminomas, choriocarcinoma, teratomas with chorioma components, other germ cell tumors, molar pregnancy, and islet cell tumors. Therefore, a positive result in a man can be used as a test for testicular cancer. The normal range for males is between 0 and 5 mIU/mL. Bound to alpha-fetoprotein, β-HCG is an excellent tumor marker for monitoring germ cell tumors.

The combination of hCG testing with AFP and other parameters such as accurate gestational age and maternal weight also helps in the risk assessment of Down syndrome. In pregnancies with Down syndrome, maternal serum AFP concentrations are reduced and serum hCG concentrations are approximately twice the normal population median.

Alpha Lifetech Inc. is dedicated to developing HCG diagnostic regents. Alpha Lifetech Inc. is a reputable supplier focusing on research, manufacture and sales of In Vitro Diagnostic (IVD) regents. All the IVD regents offered by Alpha Lifetech Inc. have undergone strict QC validation and are certified by the COA (certificate of analysis). Meanwhile, we can provide customized services according to customers' requirements. Alpha Lifetech Inc. is committed to supply high-quality, high-sensitivity antigen and antibody products for scientific research and industrial customers. In addition to regular small packages, Alpha Lifetech Inc.'s large-scale fermentation platform also allows us to provide raw material-grade IVD regents for the majority of industrial customers.

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