Once your placenta begins making hCG, it triggers your body to create more estrogen and progesterone. Together with hCG, these hormones help thicken your uterine lining and tell your body to stop menstruating (or releasing eggs). The correct balance of these three hormones sustains and supports the pregnancy.
HCG (Human Chorionic Gonadotropin) is often called the pregnancy hormone because it is made by cells formed in the placenta, which nourishes the egg after it has been fertilized and becomes attached to the uterine wall. Levels can first be detected by a blood test about 11 days after conception and about 12-14 days after conception by a urine test.
Human chorionic gonadotropin is a hormone produced primarily by syncytiotrophoblastic cells of the placenta during pregnancy. The hormone stimulates the corpus luteum to produce progesterone to maintain the pregnancy. Smaller amounts of hCG are also produced in the pituitary gland, the liver, and the colon. As previously mentioned, certain malignancies can also produce either hCG or hCG-related hormone. Trophoblastic cancers (hydatidiform mole, choriocarcinoma, and germ cell tumors) are associated with high serum levels of hCG-related molecules.
The hormone itself is a glycoprotein composed of two subunits, the alpha and beta subunits. There are multiple forms found in the serum and urine during pregnancy including the intact hormone and each of the free subunits. HCG is primarily catabolized by the liver, although about 20% is excreted in the urine. The beta subunit is degraded in the kidney to make a core fragment which is measured by urine hCG tests.
HCG is an important hormone in pregnancy, and its clinical utility is primarily centered around its detection in early pregnancy, along with serial measurement during pregnancy and pregnancy-related complications.
Patients who have hCG levels that plateau prior to 8 weeks or that fail to double commonly have a nonviable pregnancy, whether intra-uterine or extra-uterine. Extra-uterine (ectopic) pregnancies usually have a rate-of-rise that is low without the typical doubling. However, given the large range of normal hCG levels and inconsistent rates-of-rise of this hormone, checking serum levels is typically paired with ultrasound evaluation to improve sensitivity and specificity.
Human chorionic gonadotropin (hCG) is a hormone normally produced by the placenta. If you are pregnant, you can detect it in your urine. Blood tests measuring hCG levels can also be used to check how well your pregnancy is progressing.
When you are 4 weeks pregnant your body and your new baby are undergoing rapid changes. The placenta forms and begins producing a hormone called human chorionic gonadotrophin (hCG), which is the substance a pregnancy test detects to confirm you are pregnant. The cells which are growing into your new baby establish membranes which connect them to the placenta and prepare themselves for differentiation into different types of cells, which will occur next week when you are 5 weeks pregnant. These developments may cause you to experience unusual emotions and also cause changes in your body such as darkening of the areolas of your nipples.
As we know today, hCG is a hormone comprising an α-subunit and a β-subunit which are held together by non-covalent hydrophobic and ionic interactions. The molecular weight of hCG is approximately 36,000. It is an unusual molecule in that 25-41% of the molecular weight is derived from the sugar side-chains (25-30% in regular hCG and 35-41% in hyperglycosylated hCG). Today, the function of hCG is still marked as being progesterone promotion in most medical student text books, but we now know now that hCG has numerous other important placental, uterine and fetal functions in pregnancy. From the time of implantation, hCG produced by trophoblast cells take over corpus luteal progesterone production rom luteinizing hormone (LH), acting on a joint hCG/LH receptor. This continues for approximately 3 to 4 weeks. After that time, there are sufficient syncytiotrophoblast cells in the placenta to take over progesterone production from corpus luteal cells.
Research now shows that there are at least 4 independent variants of hCG, each produced by different cells with separate biological functions. All the molecules share a common hCGβ-subunit amino acid sequence. There is hCG, produced by differentiated syncytiotrophoblast cells or more specifically villous syncytiotrophoblast cells as pregnancy progresses [5-7]. This is the molecules that promotes progesterone production by ovarian corpus luteal cells and has multiple other biological functions as described below. Hyperglycosylated hCG is a sugar variant of hCG made by root cytotrophoblast cells or extravillous cytotrophoblast cells as pregnancy progresses [6,7]. Hyperglycosylated hCG is not a hormone but is an autocrine, acting on cytotrophoblast cells to promote cell growth and invasion as in implantation of pregnancy and invasion by choriocarcinoma cells [8,9]. Free β-subunit is the alternatively glycosylated monomeric variant of hCG made by all non-trophoblastic advanced malignancies . Free β-subunit promotes growth and malignancy of advanced cancers [11,12]. A fourth variant of hCG is pituitary hCG, produced during the female menstrual cycle. This molecules has sulfated rather than sialylated oligosaccharides. Pituitary hCG functions in an LH-like manner to promote follicular maturation, stigma formation and meiosis in the primary follicle, ovulation, luteinization of the follicle, and progesterone production during the menstrual cycle [13,14]. The biological activities of all 4 variants of hCG and the actions of the hCG/LH receptor are carefully investigated in this review.
It is now been 30 years since hCG was first demonstrated to originate from the pituitary gland . Since then, almost 40 publications have confirmed this observation and described how very low level hCG production accompanies luteinizing hormone (LH) production at the time of the mid-menstrual cycle pre-ovulatory surge, a normal part of normal pituitary physiology [128-134]. Most noticeably, pituitary derived hCG is normally elevated along with pituitary LH and FSH in women receiving an oophorectomy, during oligomenorrhea in perimenopause (age 40-50), and during amenorrhea in menopause (Age >50) [129-134]. In medical practice, a positive hCG test prior to menopause suggests pregnancy or gestational trophoblastic disease [132-134]. A positive hCG test in perimenopausal and menopause, can represent a predicament to physicians. When an hCG positive patient is referred to an oncologist, they may be considered as having gestational trophoblastic diseases or a non-gestational malignancy, and may be placed on chemotherapy or given hysterectomy with the hope that hCG will disappear. The hCG level will not change in patients treated this way, since it is natural hormone, pituitary hCG.
As shown by Odell and Griffin [135,136], using an ultra-sensitive radioimmunoassay LH (sensitivity 0.005 mIU/ml), pituitary hCG is produced at very low levels (mean 0.01 mIU/ml) in men, with a wide range of 0.03 to 1.7 mIU/ml. Pituitary hCG was detected in women in pulses in the luteal and follicular phases of the menstrual cycle which paralleled LH levels [135,136]. Injections of Gonadotropin releasing hormone (GnRH) were shown to directly promote circulating pituitary hCG levels in men and women, just as they similarly promotes LH levels [135,136]. It is inferred that pituitary hCG supplements pituitary LH in men and women [13,136]. The USA hCG Reference Service recently examined over 8300 urine samples from women with normal menstrual periods using the Siemens Immulite 1000 assay to total hCG [13,136]. As found, hCG (sensitivity >1 mIU/ml) was detected at the time of the mid-cycle LH peak in 232 of 277 (84%) menstrual cycles. The mean hCG level was 1.54 0.90 mIU/ml and the range was
The mass of hCG stored in an individual human pituitary gland, 0.5-1.1 μg hCG per gland, is approximately 25-50 fold less than the mass of LH . Publications show that pituitary hCG has approximately half the biological activity in promoting progesterone production of placental hCG . As such, it is 40-fold more potent than pituitary LH . As indicated by Odell and Griffin, circulating levels of hCG during the menstrual cycle are approximately 1/120th of circulating levels of LH, mIU/ml to mIU/ml [135,136]. Considering the 40-fold greater potency of pituitary hCG, pituitary hCG may therefore have an average potency of approximately 1/3rd of the potency of LH. This makes pituitary hCG a significant pituitary hormone.
Human chorionic gonadotropin (hCG) is a hormone for the maternal recognition of pregnancy produced by trophoblast cells that are surrounding a growing embryo (syncytiotrophoblast initially), which eventually forms the placenta after implantation. The presence of hCG is detected in some pregnancy tests (HCG pregnancy strip tests). Some cancerous tumors produce this hormone; therefore, elevated levels measured when the patient is not pregnant may lead to a cancer diagnosis and, if high enough, paraneoplastic syndromes, however, it is not known whether this production is a contributing cause, or an effect of carcinogenesis. The pituitary analog of hCG, known as luteinizing hormone (LH), is produced in the pituitary gland of males and females of all ages.
It is heterodimeric, with an α (alpha) subunit identical to that of luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), and β (beta) subunit that is unique to hCG.
Human chorionic gonadotropin interacts with the LHCG receptor of the ovary and promotes the maintenance of the corpus luteum for the maternal recognition of pregnancy at the beginning of pregnancy. This allows the corpus luteum to secrete the hormone progesterone during the first trimester. Progesterone enriches the uterus with a thick lining of blood vessels and capillaries so that it can sustain the growing fetus. 041b061a72