Overview
Human chorionic gonadotropin (HCG) is a glycoprotein hormone built from two linked subunits: an alpha chain shared with several pituitary hormones and a distinctive beta chain that gives HCG its specificity. In pregnancy it is produced by trophoblast tissue of the developing placenta and helps sustain the hormonal environment of early gestation, notably by supporting progesterone output from the corpus luteum. Because of its receptor activity, HCG is one of the most frequently referenced compounds in studies of the reproductive endocrine axis.
How HCG Works
HCG binds the LH/hCG receptor (LHCGR), the same receptor activated by luteinizing hormone, and reproduces LH-like signalling in the gonads. The two hormones are closely related, but HCG carries heavier glycosylation, which slows its clearance and extends its circulating half-life to roughly 24–36 hours — far longer than the minutes-scale half-life of native LH. In research models this prolonged, LH-mimicking signal is used to study processes such as corpus-luteum support, ovarian follicle maturation, and testicular steroidogenesis, where it can stimulate Leydig-cell testosterone production through the same downstream pathway as LH.
What the Research Explores
- LH/hCG receptor signalling and its role in gonadal steroid production.
- Ovulation-trigger and follicle-maturation models in assisted-reproduction research.
- Leydig-cell and testicular testosterone-production pathways.
- Corpus-luteum and progesterone-support physiology of early pregnancy.
- Use of beta-hCG as a quantitative marker in pregnancy and tumour-monitoring studies.
Forms & Handling
HCG intended for injection is supplied as a lyophilized powder dosed in International Units (IU), with the 5,000 IU vial being the most common laboratory format. It is reconstituted with a sterile diluent before use and kept refrigerated once in solution. A key measurement caution: vial dose is expressed in IU, whereas laboratory blood and urine readings are reported as concentration in mIU/mL — the two scales describe different things and are not interchangeable. See the dosing protocol below for the reconstitution math in insulin-syringe units.
Safety & Research Notes
HCG is handled here strictly as an investigational research compound; there is no approved human or veterinary use in this context and no established safety profile for self-administration. In clinical settings the hormone carries genuine risks — including ovarian hyperstimulation syndrome in fertility applications — and requires diagnosis, dosing, and follow-up monitoring by a clinician. It is also classed among testosterone-stimulating substances on anti-doping prohibited lists for male athletes. Claims that HCG drives meaningful weight loss beyond calorie restriction are unsupported, and regulators have warned against such products. Everything here is mechanistic background, not a usage recommendation.
References
- Betz D, Fane K. Human Chorionic Gonadotropin. StatPearls (NCBI Bookshelf). ncbi.nlm.nih.gov/books/NBK532950
- Choi J, Smitz J. Luteinizing hormone and human chorionic gonadotropin: distinguishing unique physiologic roles. Gynecological Endocrinology (PMC). pmc.ncbi.nlm.nih.gov/articles/PMC3956631
- Nwabuobi C, et al. hCG: biological functions and clinical applications. International Journal of Molecular Sciences (PMC). pmc.ncbi.nlm.nih.gov/articles/PMC4287577
- U.S. FDA. Avoid Dangerous HCG Diet Products (Consumer Update). fda.gov/consumers/consumer-updates/avoid-dangerous-hcg-diet-products