Overview
Following subcutaneous or intramuscular administration, HCG is absorbed into the systemic circulation with a bioavailability of approximately 75–85% via subq route. It has a biphasic elimination: an initial rapid distribution phase (t½ ~5–6 hours) followed by a longer elimination phase (t½ ~24–36 hours for the intact molecule; beta subunit t½ ~36 hours). It distributes primarily to the gonads, liver, and kidneys. HCG is metabolized via proteolytic degradation and renal filtration — urinary HCG metabolites are the basis for pregnancy tests. Clearance is reduced in renal impairment. The extended half-life compared to LH (~20 minutes) is attributable to extensive glycosylation (particularly sialylation) of the beta subunit, which masks proteolytic cleavage sites and reduces hepatic asialoglycoprotein receptor-mediated clearance.
Proposed mechanism
HCG binds to the luteinizing hormone/choriogonadotropin receptor (LHCGR) on Leydig cells in the testes, activating adenylyl cyclase via Gs protein coupling and elevating intracellular cAMP. This cascade stimulates steroidogenesis, promoting the conversion of cholesterol to testosterone and supporting spermatogenesis via Sertoli cell signaling. In women, HCG triggers ovulation by mimicking the LH surge, inducing follicular rupture and corpus luteum formation.
What the evidence supports
Randomised controlled trial data in humans exists and supports use in specific contexts.
Graded Clinical
Findings supported by randomised, controlled trials in humans, with pre-registered endpoints and published results.
Key citations
Representative primary sources, including results that did not favour the compound.
- [1]
Recombinant human chorionic gonadotropin treatment of men with idiopathic normosmic hypogonadotropic hypogonadism
· Liu PY et al. J Clin Endocrinol Metab. 2009;94(12):4837-4845. · 2009
- [2]
Human chorionic gonadotropin structure and function
· Cole LA. Clin Chim Acta. 2010;411(1-2):48-65. · 2010
- [3]
Recovery of spermatogenesis following testosterone replacement therapy or anabolic-androgenic steroid use
· Rahnema CD et al. Asian J Androl. 2015;17(6):825-829. DOI:10.4103/1008-682X.153313 · 2015
- [4]
The use of human chorionic gonadotropin for the induction of ovulation
· Papanikolaou EG et al. Hum Reprod Update. 2012;18(5):507-515. · 2012
- [5]
LHCGR desensitization by high-dose hCG
· Dufau ML. Endocr Rev. 1998;19(5):508-532. (foundational receptor biology reference) · 2003
Citation records in this build are illustrative placeholders for the design.
Reference information for research purposes. Not medical advice, and not a recommendation to use any compound. Many entries describe substances that are not approved for human use.