hCG (human chorionic gonadotropin) is a hormone produced during pregnancy by the cells that form the placenta. This hormone is detected in the blood around 11 days after conception; it is detected in the urine around 12-14 days after conception. While it is most commonly associated with pregnancy, it is present in both genders.

Human chorionic gonadotropin (American English) or Human chorionic gonadotrophin (hCG) is a glycoprotein hormone produced in pregnancy that is made by the developing embryo soon after conception and later by the syncytiotrophoblast (part of the placenta). Its role is to prevent the disintegration of the corpus luteum of the ovary and thereby maintain progesterone production that is critical for a pregnancy in humans.

hCG may have additional functions; for instance, it is thought that hCG affects the immune tolerance of the pregnancy. Early pregnancy testing, in general, is based on the detection or measurement of hCG. Because hCG is also produced by some kinds of tumors, hCG is an important tumor marker, but it is not known whether this production is a contributing cause or an effect of tumorigenesis.

Human chorionic gonadotropin is a glycoprotein composed of 244 amino acids with a molecular mass of 36.7 kDa. Its total dimensions are 75×35×30 angstroms (7.5×3.5×3 nanometers). 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. * The α (alpha) subunit is 92 amino acids long and has dimensions 60×25×15 angstroms (6×2.5×1.5 nm).

* The β-subunit of hCG gonadotropin contains 145 amino acids and has dimensions 6.5×2.5×2 nm, encoded by six highly-homologous genes that are arranged in tandem and inverted pairs on chromosome 19q13.3 - CGB (1, 2, 3, 5, 7, 8). B The two subunits create a small hydrophobic core surrounded by a high surface areato-volume ratio: 2.8 times that of a sphere. The vast majority of the outer amino acids are hydrophilic.

hCG signals the hypothalamus (area of the brain that affects metabolism) to mobilize fat stores. In pregnancy, this helps the body bring nutrients into the placenta, fueling the fetus with the energy to grow. Human chorionic gonadotropin interacts with the LHCG receptor and promotes the maintenance of the corpus luteum during the beginning of pregnancy, causing it to secrete the hormone progesterone. Progesterone enriches the uterus with a thick lining of blood vessels and capillaries so that it can sustain the growing fetus. Due to its highly negative charge, hCG may repel the immune cells of the mother, protecting the fetus during the first trimester. It has also been hypothesized that hCG may be a placental link for the development of local maternal immunotolerance. For example, hCG-treated endometrial cells induce an increase in T cell apoptosis (dissolution of T-cells). These results suggest that hCG may be a link in the development of peritrophoblastic immune tolerance, and may facilitate the trophoblast invasion, which is known to expedite fetal development in the endometrium. [1] It has also been suggested that hCG levels are linked to the severity of morning sickness in pregnant women.[2] Because of its similarity to LH (leutinizing hormone), hCG can also be used clinically to induce ovulation in the ovaries as well as testosterone production in the testes. As the most abundant biological source is women who are presently pregnant, some organizations collect urine from pregnant women to extract hCG for use in fertility treatment. hCG (human chorionic gonadotropin) is the only hormone in the Glycoprotein family not produced by the anterior pituitary but by the placental trophoblast. (Thus detection of the HCG is the basis of pregnancy tests). HCG is very similar to LH and has essentially the same function as LH. Human chorionic gonadotropin also plays a role in cellular differentiation/proliferation and may activate apoptosis. (Cell death) Like other gonadotropins, hCG can be extracted from urine or by genetic modification.

Testing

Levels of hCG may be measured in the blood or urine. Most commonly, this is done as a pregnancy test, intended to indicate the presence or absence of an implanted embryo. Testing for hCG may also be done when diagnosing or monitoring germ cell tumors and gestational trophoblastic disease.

A controversial usage of hCG is as an adjunct to the British endocrinologist Dr. A.T.W. Simeons' ultra-low-calorie weight-loss diet. [7] Simeons, while studying pregnant women in India on a calorie-deficient diet, and "fat boys" with pituitary problems treated with low-dose hCG, discovered that both lost fat rather than lean (muscle) tissue. He reasoned that hCG must be programming the hypothalamus to do this in the former cases in order to protect the developing fetus, and proceeded to use lowdose daily hCG injections (125 mg) in combination with a customized ultra-low-calorie (500 cal/day, high-protein, low-carbohydrate/fat) diet to help obese adults lose dramatic amounts of adipose tissue without loss of lean tissue, at a Salvator Mundi International Hospital in Rome, Italy, clinic mainly for celebrities. After Simeons' mysterious death, the diet started to spread to specialized centers and via popularization The controversy proceeds from warnings by the Journal of the American Medical Association [8] and the American Journal of Clinical Nutrition[9] that hCG is not safe,[8]