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What is HCG?
Human chorionic gonadotropin (HCG) is a glycoprotein hormone composed of 237 amino acids, with a total molecular mass of approximately 36.7 kDa. It is a heterodimer consisting of a non-covalently bound alpha subunit (14.5 kDa) and a beta subunit (22.2 kDa). The alpha subunit is structurally shared with three other pituitary glycoprotein hormones: luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH). The beta subunit of HCG confers its biological specificity and provides the basis for its use in pregnancy testing, as it is distinct from the LH beta subunit at the C-terminal extension.
HCG exerts its primary biological effects by binding to the LH/HCG receptor, a G protein-coupled receptor expressed on gonadal tissue. In males, this receptor is located on Leydig cells in the testes, where HCG binding stimulates the production of testosterone, the primary androgen responsible for secondary sexual characteristics, spermatogenesis support, and anabolic activity. In females, HCG binds to receptors on the corpus luteum, stimulating progesterone production and supporting the luteal phase during early pregnancy.
HCG has well-established FDA-approved clinical indications. In males, it is approved for the treatment of prepubertal cryptorchidism (undescended testes) and hypogonadotropic hypogonadism. In females, it is approved for the induction of ovulation in women who fail to ovulate due to anovulatory conditions, and as a component of assisted reproductive technology protocols.
In the context of androgen replacement therapy and post-cycle recovery from androgenic anabolic steroid use, HCG is used to maintain or restore endogenous testosterone production and testicular function. Exogenous testosterone suppresses LH secretion via negative feedback on the pituitary, leading to testicular atrophy and cessation of spermatogenesis over time. Periodic HCG administration bypasses the suppressed LH signal and directly stimulates Leydig cell testosterone production, preserving testicular size and function [1].
Research Supply
Source high-purity HCG for your research
Dosage Guide
Route: Intramuscular (IM) or subcutaneous (SQ) injection
Dosing Schedule
| Period | Dose |
|---|---|
| Cryptorchidism (children 4-9 years) | 4,500 IU 3x weekly for 4-6 weeks |
| Hypogonadotropic hypogonadism (males) | 500-1,000 IU 3x weekly IM for 3 weeks, then 2x/week x 3 weeks |
| Ovulation induction (females) | 5,000-10,000 IU single dose after follicle maturation |
| TRT adjunct / testicular maintenance | 250-500 IU every 3-4 days SQ |
| Post-cycle recovery | 500-1,000 IU daily or every other day SQ for 10-14 days |
Reconstitution
Injection Volumes
| Dose | Volume | Syringe Units |
|---|
Administration Tips
- HCG is supplied as a lyophilized powder and requires reconstitution with bacteriostatic water for injection
- Refrigerate reconstituted solution and use within 30 to 60 days depending on concentration and storage conditions
- Dosing varies considerably by indication; clinical doses for fertility are substantially higher than doses for testicular maintenance
- Monitor with laboratory testing (total testosterone, LH, FSH, estradiol as relevant)
- HCG can aromatize to estrogen via peripheral aromatase enzymes, particularly at higher doses; managing estrogen with an aromatase inhibitor may be necessary
Risks & Side Effects
Commonly Reported
Serious Risks
Ovarian hyperstimulation syndrome (OHSS)
A potentially life-threatening condition in women characterized by massively enlarged ovaries, fluid shifts into the abdominal and pleural cavities, hemoconcentration, and thromboembolism risk. Risk is highest in women with polycystic ovarian morphology.
Multiple gestation
Use of HCG in ovulation induction protocols carries a risk of multiple embryo implantation and multiple pregnancy.
Thromboembolism
Elevated sex hormones carry prothrombotic risk, particularly at high doses.
Leydig cell desensitization
Chronic LH/HCG receptor overstimulation from very high or continuous HCG use can paradoxically reduce Leydig cell responsiveness.
Acceleration of androgen-sensitive malignancies
HCG-stimulated testosterone may worsen prostate cancer and other androgen-sensitive conditions.
Contraindications
- Androgen-sensitive malignancies (prostate cancer, testicular cancer)
- Primary testicular failure (where Leydig cells cannot respond to LH/HCG signaling)
- Precocious puberty in pediatric patients
- Pregnancy in women (except in specific assisted reproduction contexts under specialist supervision)
- Hypersensitivity to HCG or formulation components
- Ovarian cysts or enlargement not related to polycystic ovarian syndrome
- Uncontrolled thyroid or adrenal disorders
Related Peptides
Experts Covering HCG
LEGAL DISCLAIMER
The information provided on this page is for educational and informational purposes only and is not intended as medical advice. HCG is FDA-approved for specific indications; use outside of those approved indications is off-label. Always consult with a qualified healthcare professional before starting any peptide therapy. Individual results may vary. Peptides Institute is not responsible for any adverse effects resulting from the use of information provided on this site.
Frequently Asked Questions
What is HCG and what is it used for?
How does HCG help during testosterone replacement therapy?
What is the HCG dosage for post-cycle therapy?
Does HCG cause estrogen side effects?
What are HCG side effects?
Is HCG FDA approved?
References
- Coviello AD, Matsumoto AM, Bremner WJ, et al.. Low-dose human chorionic gonadotropin maintains intratesticular testosterone [^1] in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab. 2005. PMID 15713727
- Hsieh TC, Pastuszak AW, Hwang K, et al.. preserves spermatogenesis in men undergoing testosterone replacement therapy [^2]. J Urol. 2013. PMID 23260550
- Fink J, Matsumoto M, Tamura Y. Human chorionic gonadotropin treatment: a viable option for management of secondary hypogonadism and male infertility. Expert Rev Endocrinol Metab. 2021. PMID 33345656
Regulatory & Official Sources
- Human chorionic gonadotropin — Wikipedia