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.
Because of its similarity to LH, 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 gravidae to extract hCG for use in fertility treatment.
Most tests employ a monoclonal antibody (MAb), which is specific to the β-subunit of hCG (βhCG). This procedure is employed to ensure that tests do not make false positives by confusing hCG with LH and FSH. (The latter two are always present at varying levels in the body, whereas the presence of hCG almost always indicates pregnancy.)
Gestational trophoblastic disease like Hydatidiform moles ("molar pregnancy") or Chroiocarcinoma may produce high levels of βhCG (due to the presence of syncytialtrophoblasts- part of the villi that make up the placenta) despite the absence of an embryo. This, as well as several other conditions, can lead to elevated hCG readings in the absence of pregnancy.
In the male, hCG injections are used to stimulate the leydig cells to synthesize testosterone. The intratesticular testosterone is necessary for spermatogenesis from the sertoli cells. Typical uses for hCG in men include hypogonadism and fertility treatment.
During first few months of pregnancy, the transmission of HIV-1 from woman to fetus is extremely rare. It has been suggested that this is due to the high concentration of hCG, and that the beta-subunit of this protein is active against HIV-1.
In the world of performance enhancing drugs, hCG is increasingly used in combination with various anabolic androgenic steroid (AAS) cycles.
When AAS are put into a male body, the body's natural negative-feedback loops cause the body to shut down its own production of testosterone via shutdown of the hypothalamic-pituitary-gonadal axis (HPGA). High levels of AASs that mimic the body's natural testosterone trigger the hypothalamus to shut down its production of gonadotropin-releasing hormone (GnRH) from the hypothalamus. Without GnRH, the pituitary gland stops releasing luteinizing hormone (LH). LH normally travels from the pituitary via the blood stream to the testes, where it triggers the production and release of testosterone. Without LH, the testes shut down their production of testosterone, causing testicular atrophy.
In males, hCG mimics LH and helps restore and maintain testosterone production in the testes. As such, hCG is commonly used during and after steroid cycles to maintain and restore testicular size as well as endogenous testosterone production. However, if hCG is used for too long and in too high a dose, the resulting rise in natural testosterone will eventually inhibit its own production via negative feedback on the hypothalamus and pituitary.
Elevated cerebrospinal fluid levels of placental alkaline phosphatase and [beta]-human chorionic gonadotrophin in a case of intracranial germinoma with normal levels in blood
Oct 01, 2007; Sir, The authors report a case of intracranial germinoma with raised levels of β -human chorionic gonadotrophin (HCG) and...
Prediction of Testosterone Response to Human Chorionic Gonadotrophin in Idiopathic Hypogonadotropic Hypogonadism Patients
Jan 01, 2009; In clinical practice, the human chorionic gonadotrophin (hCG) stimulation test is widely used to evaluate testicular function....
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Feb 16, 2011; Authors: Xiaojie Sun (equal contributor) ; Shuqi Mei (equal contributor) ; Hu Tao ; Guodong Wang ; Lina Su ; Siwen...