HCG
Human Chorionic Gonadotropin
HCG is a glycoprotein hormone that acts as a structural and functional analogue of LH (luteinizing hormone) — binding the LH/HCG receptor on Leydig cells to drive testosterone production and on ovarian granulosa cells to trigger ovulation. It is FDA approved for multiple indications and has extensive clinical use in reproductive medicine.
At a Glance
HCG's beta subunit determines its LH-like activity. The two share a common alpha subunit but differ at the beta chain — HCG's extended beta C-terminal peptide (CTP) gives it a much longer half-life than LH (~24 hours vs ~1 hour), making it more practical for clinical and research protocols.
In male research contexts, HCG is used to maintain testicular function during TRT (preventing testicular atrophy) and to restore spermatogenesis. In female fertility research, it triggers the LH surge equivalent for oocyte maturation and ovulation induction.
Its cross-reactivity with TSH receptors at high concentrations is also studied — explaining the hyperthyroidism sometimes observed in gestational trophoblastic disease where HCG levels are extremely elevated.
This compound operates through several converging biological pathways, which helps explain the breadth of effects observed across different tissue and metabolic models.
LH Receptor Agonism
Binds LH/HCG receptors on Leydig cells to stimulate testosterone synthesis — the direct LH analogue mechanism with 24-hour half-life.
Leydig Cell Stimulation
Drives intratesticular testosterone production — the mechanism used to maintain testicular volume and function during exogenous TRT.
Ovulation Triggering
In women, binds LH receptors on follicles to trigger oocyte maturation and ovulation — used in ART (assisted reproductive technology) protocols.
Spermatogenesis Support
FSH + HCG combination protocols restore spermatogenesis in hypogonadotropic hypogonadism — intratesticular testosterone is essential for sperm maturation.
Preclinical and clinical models have investigated this compound across a wide range of physiological contexts and tissue types.
- Male hypogonadism and TRT adjunct — testicular volume maintenance and spermatogenesis preservation
- IVF and ART — ovulation triggering (oocyte maturation induction)
- Spermatogenesis restoration — in combination with FSH for hypogonadotropic hypogonadism
- Undescended testes (cryptorchidism) — FDA-approved indication
- Intratesticular testosterone studies — central role in male reproductive physiology
- Comparison with kisspeptin as ovulation trigger — OHSS risk differential
- HPG axis characterization — Leydig cell responsiveness testing
HCG's long half-life and direct LH receptor action make it the most practical tool for Leydig cell stimulation and ovulation triggering in both clinical and research contexts.
HCG vs kisspeptin for IVF triggering is one of the most active comparisons in reproductive medicine research — direct LH receptor activation vs physiological LH surge induction.
| Aspect | HCG | LH (native) | Kisspeptin |
|---|---|---|---|
| Half-Life | ~24 hours | ~1 hour | ~28 min (kisspeptin-10) |
| Primary Action | Direct LH receptor agonism | Direct LH receptor agonism | Triggers endogenous LH surge |
| FDA Status | Approved (multiple) | Not used as drug | Not approved |
| OHSS Risk (IVF) | High | High | Lower |
| Male Research Use | TRT adjunct, spermatogenesis | Reference only | HPG axis gating |
The following reflects findings from published preclinical and clinical safety assessments where available.
FDA approved across multiple indications — extensive human safety and efficacy data
Long half-life vs native LH — 24-hour vs 1-hour, enabling practical dosing
Preserves testicular function during TRT — the standard tool for maintaining intratesticular testosterone
OHSS risk in IVF — the sustained LH-like stimulus can cause ovarian hyperstimulation; kisspeptin being explored as safer alternative
This overview is strictly educational and based on publicly available scientific literature as of 2026. It does not constitute medical advice. All Helixera Labs products are for laboratory research use only. Not for human or veterinary use. · Helixera Labs LLC © 2026