HCG research

The HCG evidence base cited here is 4 sources — 2 clinical, 1 review. Its strongest evidence is human — 2 clinical studies, most recently 2019 ("Human Chorionic Gonadotropin Monotherapy for the Treatment of Hypogonada…"). Regulatory status: FDA-approved.

• HCG is a large (~37 kDa) glycoprotein hormone — the second big glycoprotein in this collection alongside follistatin — naturally produced by the placenta. It is a genuine FDA-approved drug for specific indications.
• It activates LH receptors: in men it stimulates testicular testosterone production (used to maintain testicular function and fertility during TRT and to treat hypogonadism/cryptorchidism); in women it triggers final oocyte maturation/ovulation.
• It has real clinical-trial backing across fertility and cryptorchidism uses — unlike most research peptides — though many bodybuilding/TRT-adjunct uses are off-label.

Human chorionic gonadotropin (HCG) is a glycoprotein hormone of pregnancy that mimics luteinizing hormone (LH). Pharmaceutically it is either urinary-derived (e.g. Pregnyl, Novarel) or recombinant (Ovidrel), and it is FDA-approved for hypogonadism, infertility, and cryptorchidism. In TRT practice it is widely used to keep the testes functioning while exogenous testosterone suppresses the natural signal.

It is a regulated hormone drug; everything below is research/clinical context, not medical guidance.

HCG is a heterodimeric glycoprotein (~36,700 Da) made of two non-covalently linked subunits: an alpha subunit identical to that of LH, FSH, and TSH, and a unique beta subunit that gives HCG its specific activity. The beta subunit carries a 24-amino-acid C-terminal extension not found in LH, and the molecule is heavily glycosylated (~30% carbohydrate), which extends its half-life and shapes receptor binding.

That heavy glycosylation also explains why urinary-derived and recombinant versions differ slightly — their glycosylation patterns aren't identical.

HCG binds and activates LH receptors. On testicular Leydig cells that drives testosterone (and some estrogen) biosynthesis — which is why it preserves testicular size and intratesticular testosterone (and therefore fertility) during testosterone-replacement therapy that would otherwise shut the testes down. In women it acts on ovarian theca cells to stimulate progesterone and triggers the final maturation and release of the egg, which is its role as an ovulation 'trigger shot'.

• Half-life: ~24–36 hours (≈1.5 days initial)

• Spermatogenesis induction with HCG/FSH (2018 review): the combination induces spermatogenesis in ~70–90% of men with hypogonadotropic hypogonadism.
• Cryptorchidism (2014 Cochrane meta-analysis, 1,231 boys): ~25% success for hormonal treatment; surgery is more effective, but HCG/GnRH may have a role in selected cases.

HCG is an FDA-approved prescription drug for hypogonadism, infertility, and cryptorchidism. Other uses (TRT adjunct, PCT, the 'HCG diet') are off-label or, in the case of HCG-for-weight-loss, not supported and previously the subject of FDA action against OTC homeopathic claims. It is also prohibited for male athletes under WADA (it can be used to stimulate endogenous testosterone).

All citations link to the original source (PubMed, journal site, or regulatory filing). Independent research database — no vendor influence on what's cited.