hCG

A heterodimeric glycoprotein hormone (CAS 9002-61-3, ~237 aa across its α- and β-subunits, ~36.7 kDa glycosylated) produced by placental syncytiotrophoblast during pregnancy. Agonizes the luteinizing hormone / choriogonadotropin receptor (LHCGR), functionally mimicking LH — one step downstream of Gonadorelin and Kisspeptin-10 in the reproductive axis. FDA-approved formulations include urinary-derived hCG (Pregnyl, Novarel) and recombinant choriogonadotropin alfa (Ovidrel), indicated for ovulation induction in female infertility and male hypogonadotropic hypogonadism; commonly used off-label alongside exogenous testosterone to preserve endogenous Leydig-cell testosterone production and testicular volume during HPG-axis suppression. Sold alongside research peptides rather than as one — a glycoprotein hormone, not a synthetic peptide — grouped here because of overlapping HPG-axis research use. Dosed and priced in International Units (IU) rather than mg, so $/mg comparisons against other peptides in this catalog are not meaningful; vendor vial sizes are typically 5,000 IU.