HCG: Human Chorionic Gonadotropin
A glycoprotein hormone studied for its LH-mimetic activity and gonadal stimulation research.
Quick Reference
| Research Dosage | 1000-2000 IU, 2-3 times weekly |
|---|---|
| Frequency | 2-3 times per week |
| Administration | Subcutaneous or intramuscular |
| Protocol Length | 3-6 months typical |
| Reconstitution | 2mL bacteriostatic water |
| Storage | Refrigerate only - do NOT freeze |
HCG is fundamentally different from peptides – it's a large glycoprotein hormone (~37,000 Da) consisting of alpha and beta subunits. To put this in perspective, most peptides are 500-5,000 Da; HCG is nearly 10 times larger than the biggest common peptides.
Naturally produced during pregnancy by placental cells, HCG is studied for its ability to mimic luteinizing hormone (LH) and stimulate gonadal function. The LH-mimetic activity is possible because HCG shares a receptor with LH – the LH/CG receptor.
A key advantage of HCG over LH for research: HCG has a much longer half-life (24-36 hours vs. ~30 minutes for LH), making it more practical to work with.
Research Applications
HCG is primarily studied in reproductive endocrinology and fertility research due to its LH-mimetic properties:
LH-Mimetic Effects
HCG binds to and activates the LH/CG receptor:
- Stimulates Leydig cells in testes
- Triggers testosterone synthesis
- Mimics LH's effects with longer duration
- Half-life: 24-36 hours (vs. 30 min for LH)
Testosterone Research
- Stimulates endogenous testosterone production
- Maintains testicular function and size
- Research into HPG (hypothalamic-pituitary-gonadal) axis
- Testosterone regulation studies
Male Fertility Research
- Supports spermatogenesis (sperm production)
- Maintains high intratesticular testosterone (required for sperm production)
- Fertility preservation applications
- Hypogonadism research
Female Fertility Research
- Ovulation induction (triggers LH surge effect)
- IVF protocols
- Luteal phase support
- Reproductive endocrinology research
Dosage Information
Standard Research Dosages
Dosages commonly referenced in research literature range from 1000-2000 IU, administered 2-3 times weekly. Dosing frequency is based on HCG's 24-36 hour half-life.
Administration Routes
HCG can be administered via subcutaneous or intramuscular injection. Both routes demonstrate effective absorption and biological activity.
Protocol Duration
Research protocols typically range from 3-6 months for most applications. Duration depends on the specific research objectives and endpoints being measured.
Reconstitution Guide
Required Materials
- HCG lyophilised powder (5000 IU vial)
- Bacteriostatic water (water containing 0.9% benzyl alcohol)
- Sterile syringe for reconstitution
- Alcohol swabs for sterile technique
Reconstitution Steps
- Allow the HCG vial to reach room temperature before reconstitution
- Draw 2mL of bacteriostatic water into the syringe
- Insert the needle into the HCG vial and direct the stream of water down the inside wall of the vial – do not spray directly onto the powder
- Allow the powder to dissolve naturally without shaking. Gentle swirling is acceptable if needed. The solution should be clear with no visible particles.
- Store reconstituted solution refrigerated at 2-8°C immediately after reconstitution
Concentration Reference
| Vial Size | Water Added | Concentration | 1000 IU Dose | 1500 IU Dose |
|---|---|---|---|---|
| 5000 IU | 2mL | 2500 IU/mL | 40 units (0.4mL) | 60 units (0.6mL) |
| 5000 IU | 2.5mL | 2000 IU/mL | 50 units (0.5mL) | 75 units (0.75mL) |
Storage Guidelines – Critical
Do NOT Freeze HCG
Unlike most peptides, HCG should never be frozen. Freezing damages the glycoprotein structure and can eliminate biological activity.
Lyophilised (Powder) Form
- Refrigerate at 2-8°C for optimal stability
- Stable for extended periods as lyophilised powder
- Protect from light and moisture
- Keep vial sealed until ready for reconstitution
Reconstituted Solution
- Must be refrigerated at 2-8°C
- Stable for approximately 60 days when stored correctly
- Do not freeze after reconstitution – freezing damages the protein structure
- Glycoprotein structure is sensitive to freeze-thaw cycles
- Use sterile technique when drawing doses to prevent contamination
- If solution becomes cloudy or contains particles, discard and reconstitute a fresh vial
Frequently Asked Questions
Common questions about HCG research
Why can't HCG be frozen?
HCG is a glycoprotein with complex tertiary structure and sugar attachments. Freezing can disrupt this structure, reducing or eliminating biological activity. Unlike most peptides which tolerate freezing well, HCG must be refrigerated only at 2-8°C.
Why is HCG measured in IU instead of mg?
International Units (IU) measure biological activity, not mass. This is standard for hormones where activity varies with preparation. IU ensures consistent biological potency across different batches and manufacturing methods.
How is HCG different from peptides?
HCG is much larger (~37,000 Da vs. 500-5,000 Da for most peptides) and is a glycoprotein (has sugar attachments). Most peptides are simple amino acid chains without glycosylation. HCG consists of two subunits (alpha and beta) forming a heterodimer structure.
Is HCG the same as the hormone in pregnancy tests?
Yes. Pregnancy tests detect the HCG produced by placental cells during pregnancy. Research HCG is the same molecule, synthetically or recombinantly produced to identical specifications.
Why is HCG preferred over LH for research?
HCG has a much longer half-life (24-36 hours vs. approximately 30 minutes for LH), making it more practical to work with. Both activate the same LH/CG receptor, but HCG's extended duration allows for more manageable dosing schedules in research protocols.
How long does reconstituted HCG remain stable?
Reconstituted HCG remains stable for approximately 60 days when properly refrigerated at 2-8°C. The lyophilised (powder) form is stable for extended periods under proper storage conditions.
What is the LH/CG receptor?
The LH/CG receptor is a G-protein coupled receptor found primarily on Leydig cells in the testes and theca/granulosa cells in the ovaries. Both luteinizing hormone (LH) and human chorionic gonadotropin (HCG) activate this receptor, triggering steroidogenesis and hormone production.
The Science: How HCG Works
Glycoprotein Structure
HCG is a heterodimeric glycoprotein consisting of two subunits:
- Alpha subunit: Shared with LH, FSH, and TSH – provides the common structural framework
- Beta subunit: Unique to HCG – confers receptor specificity and biological activity
- Glycosylation: Sugar attachments affect half-life and biological activity
LH/CG Receptor Activation Cascade
The mechanism of HCG action follows a well-characterised signalling pathway:
- HCG binds to the LH/CG receptor (G-protein coupled receptor)
- Receptor activation increases intracellular cAMP
- In Leydig cells: Steroidogenesis pathway activation
- StAR protein facilitates cholesterol conversion to pregnenolone
- Downstream enzymatic steps produce testosterone
Why HCG Over LH for Research?
For research purposes, HCG is preferred over LH because:
- Much longer half-life (24-36 hours vs. ~30 minutes)
- Greater molecular stability
- More practical dosing schedule
- Same receptor activation and biological effects
Comparison: HCG vs. Typical Peptides
| Property | HCG | Typical Peptides |
|---|---|---|
| Molecular Weight | ~37,000 Da | 500-5,000 Da |
| Structure | Glycoprotein (2 subunits) | Linear amino acid chain |
| Glycosylation | Yes | No |
| Can Be Frozen | No | Yes |
| Measurement Unit | International Units (IU) | Milligrams/Micrograms |
Technical Specifications
| Type | Glycoprotein hormone |
| Structure | Alpha + Beta heterodimer |
| Molecular Weight | ~37,000 Da |
| Half-Life | 24-36 hours |
| Target | LH/CG Receptor |
| Glycosylation | Yes (affects activity/half-life) |
| FDA Status | Approved (fertility indications) |
| Storage | Refrigerate only (no freezing) |
| Reconstituted Stability | 60 days |
Quality: Australian University Testing
Why Peptide Quality Matters
The research peptide market contains products of highly variable quality. Independent testing of products from various suppliers has revealed significant issues:
- Purity levels as low as 50% in products claiming "99% purity"
- Incorrect amino acid sequences (entirely wrong peptides)
- Truncated sequences (missing amino acids)
- Bacterial endotoxin contamination
- Oxidised or degraded peptides with reduced activity
Our Testing Protocol
Every batch of HCG from PurposeLabs undergoes comprehensive testing at a leading proteomics laboratory based at an Australian university in Sydney – one of Australia's premier analytical facilities.
Confirms purity levels of ≥99%, identifies any impurities or degradation products.
Verifies exact molecular weight, confirms correct amino acid sequence.
Determines actual peptide content versus salt, moisture, and counter-ions.
Why Australian University Testing?
Our testing partner is an established, verifiable proteomics facility at a major Australian university, with published research credentials, transparent methodology, and no commercial conflict of interest. This contrasts with overseas "certificates of analysis" from unknown or unverifiable laboratories.
Shop HCG
Australian university tested. 99%+ purity verified by HPLC and mass spectrometry. Fast shipping from Sydney.
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References
Key studies for researchers seeking primary literature:
- Cole LA. "Biological functions of hCG and hCG-related molecules." Reproductive Biology and Endocrinology, 2010.
- Choi J, Smitz J. "Luteinizing hormone and human chorionic gonadotropin: origins of difference." Molecular and Cellular Endocrinology, 2014.
- Casarini L, et al. "LH and hCG action on the same receptor results in quantitatively and qualitatively different intracellular signalling." PLoS ONE, 2012.
- Riccetti L, et al. "Human LH and hCG stimulate differently the early signalling pathways but result in equal testosterone synthesis in mouse Leydig cells in vitro." Reproductive Biology and Endocrinology, 2017.
- Huhtaniemi I. "A short evolutionary history of FSH-stimulated spermatogenesis." Hormones, 2015.
- Ascoli M, et al. "The lutropin/choriogonadotropin receptor, a 2002 perspective." Endocrine Reviews, 2002.
- Stenman UH, et al. "The classification, functions and clinical use of different isoforms of HCG." Human Reproduction Update, 2006.
- Lapthorn AJ, et al. "Crystal structure of human chorionic gonadotropin." Nature, 1994.
Disclaimer
All products sold by PurposeLabs are intended for laboratory and research use only. They are not intended for human or animal consumption. The information provided is for educational purposes only and should not be construed as medical advice. Consult with qualified healthcare professionals for any health-related decisions.
HCG is not approved by the TGA for therapeutic use in Australia. Products are sold strictly for research purposes in accordance with Australian regulations.