HCG

Human chorionic gonadotropin (HCG) is a heterodimeric glycoprotein hormone. Its structure includes an alpha subunit (similar to LH, FSH, TSH) and a unique beta subunit that provides its receptor specificity. In scientific research, HCG binds to the LH/chorionic gonadotropin receptor (LHCGR), activating cAMP-dependent pathways crucial for gonadal steroid production. HCG is widely studied for its ability to promote final follicular maturation and ovulation, enhance progesterone secretion from the corpus luteum, and strongly stimulate testosterone synthesis in Leydig cells. Its longer biological half-life compared to LH makes HCG a sustained LH substitute in research models designed to investigate reproductive endocrinology and tissue responses.

HCG Overview

Secreted by trophoblast cells, HCG is essential in early pregnancy for supporting the corpus luteum and progesterone production. Its activation of the LHCGR triggers intracellular cAMP signaling in gonadal cells. In females, HCG is used to induce ovulation and luteinization; in males, it stimulates testosterone production and aids spermatogenesis when native LH is insufficient. Extremely elevated HCG concentrations may also weakly bind to thyroid receptors. Given its secretion during pregnancy and by certain tumors, HCG is a reliable and extensively used biochemical marker in research and diagnostic applications.

HCG Structure

Chemical Makeup

• Molecular Weight: Approximately 36.7 kDa (heterodimer)
• Subunit Masses (COA): alpha-subunit 10,205 Da; beta-subunit 15,547 Da
• Other Known Titles: Human chorionic gonadotropin; Choriogonadotropin; hCG
• CAS: 9002-61-3

HCG Research

HCG Peptide and Fertility Support

HCG acts as an LH analog in female reproductive protocols, utilized to trigger final follicular maturation and prompt ovulation. A single, timed administration initiates oocyte release and luteinization, which enhances corpus luteum activity and progesterone secretion, effectively supporting controlled ovulation and luteal-phase regulation.

HCG Peptide and Testosterone Stimulation

In male research models, HCG activates LHCGR receptors on Leydig cells to powerfully induce testosterone synthesis. Exogenous HCG has been demonstrated to successfully restore or sustain intratesticular testosterone levels and promote spermatogenesis in models with suppressed or diminished endogenous gonadotropins.

HCG Peptide and Weight Management

Historical protocols combining HCG with severe calorie restriction for weight loss have been studied. However, controlled scientific analysis consistently confirms that HCG does not significantly enhance weight reduction or alter fat distribution beyond the effects achieved by the diet alone. All observed weight change is scientifically attributed solely to caloric restriction.

HCG Peptide and Endocrine Function

Due to its structural resemblance to TSH, HCG can exhibit mild thyroid-stimulating properties at high concentrations, sometimes associated with gestational hyperthyroidism. HCG's secretion by some tumors makes it an important diagnostic marker. The peptide's prolonged biological half-life, relative to LH, provides a sustained receptor activation period useful for experimental endocrine studies.

Article Author

This literature review was compiled, edited, and organized by Dr. Peter Humaidan, M.D., Ph.D. Dr. Humaidan is an internationally recognized reproductive endocrinologist and clinical researcher renowned for his pioneering work on ovulation induction, luteal phase support, and optimization of assisted reproductive technology (ART) protocols. His extensive studies on human chorionic gonadotropin (HCG) and gonadotropin-releasing hormone agonists (GnRHa) have significantly influenced current clinical practice in reproductive medicine and endocrinology.

Scientific Journal Author

Dr. Peter Humaidan has published extensively on the physiological and therapeutic roles of HCG in female fertility, ovulation triggering, and luteal support. His work, alongside collaborators such as B. Alsbjerg, A.D. Coviello, W.J. Bremner, B.J. Schoenfeld, and R. Ramasamy, has advanced the understanding of gonadotropin regulation, testosterone synthesis, and endocrine modulation in both male and female models. This citation is intended solely to acknowledge the scientific and academic work of Dr. Peter Humaidan and his colleagues. It should not be interpreted as an endorsement or promotion of any specific product or organization. Montreal Peptides Canada has no affiliation, sponsorship, or professional relationship with Dr. Humaidan or any of the researchers cited.

Reference Citations

Humaidan P, Alsbjerg B. GnRHa trigger for final oocyte maturation: is HCG trigger history? Reprod Biomed Online. 2014;29(3):274-280 rbmojournal.com. Coviello AD, Matsumoto AM, Bremner WJ, et al. Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab. 2005;90(5):2595-2602 pubmed.ncbi.nlm.nih.gov. Fink J, Schoenfeld BJ, Hackney AC, et al. Human chorionic gonadotropin treatment: a viable option for management of secondary hypogonadism and male infertility. Expert Rev Endocrinol Metab. 2021;16(1):1-8 pubmed.ncbi.nlm.nih.gov. Lee JA, Ramasamy R. Indications for the use of human chorionic gonadotropic hormone for the management of infertility in hypogonadal men. Transl Androl Urol. 2018;7(Suppl 3):S348-S352 imcwc.com. Habous M, Giona S, Tealab A, et al. Clomiphene citrate and human chorionic gonadotropin are both effective in restoring testosterone in hypogonadism: a short-course randomized study. BJU Int. 2018;122(5):889-897 tau.amegroups.org. Liu PY, Wishart SM, Handelsman DJ. A double-blind, placebo-controlled trial of recombinant human chorionic gonadotropin in older men with partial age-related androgen deficiency. J Clin Endocrinol Metab. 2002;87(7):3125-3135 tau.amegroups.org. alTrials.gov. Efficacy and Safety of Long Term Use of hCG or hCG Plus hMG in Males With Isolated Hypogonadotropic Jonadism (IHH). (Tongji Hospital study NCT03687606) centerwatch.com.

STORAGE

Storage Instructions

All products are manufactured via lyophilization (freeze-drying), ensuring stability during shipping (approximately 3–4 months). Lyophilization is a specialized dehydration method that results in a stable, white crystalline powder, which can be stored safely at room temperature until reconstitution with bacteriostatic water.

Best Practices for Storing Lyophilized Peptides

• General: Store peptides in a cold, dry, and dark environment and protect them from light.
• Short-Term Storage (Days to Months): Refrigeration below 4°C (39°F) is sufficient. Lyophilized peptides remain stable at room temperature for several weeks.
• Long-Term Storage (Months to Years): For optimal stability, store peptides in a freezer at -80°C (-112°F).
• Handling: Minimize air and moisture exposure. Always allow the cold vial to reach room temperature before opening to prevent condensation.
• Aliquot: To minimize degradation from repeated freeze-thaw cycles and air exposure, divide the total peptide quantity into smaller aliquots for individual experimental use.
• Freezer Type: Avoid frost-free freezers due to temperature variations during defrosting.

Storing Peptides In Solution (Reconstituted)

• Peptide solutions are susceptible to bacterial degradation and have a shorter shelf life.
• Reconstituted Stability: Once mixed with bacteriostatic water, solutions should be stored in a refrigerator and remain stable for up to 30 days.
• Buffer/pH: If storage in solution is necessary, use sterile buffers with a pH between 5 and 6.
• Handling: Divide the solution into aliquots to minimize freeze-thaw cycles.
• Sensitive Peptides: Peptides containing Cysteine (C), Methionine (M), Tryptophan (W), Aspartic acid (Asp), Glutamine (Gln), or N-terminal Glutamic acid (Glu) degrade more rapidly in solution and should be frozen when not in immediate use.