HCG (Human Chorionic Gonadotropin)

HCG (human chorionic gonadotropin) is a protein-based hormone in the gonadotropin group, naturally produced in the placenta and studied in reproductive and endocrine research. It is formed from two joined subunits: an alpha subunit shared with related gonadotropins, and a distinct beta subunit that gives HCG its individual identity.

In laboratory contexts, HCG is generally classified as a hormone rather than a peptide chain, distinguishing it from many other research compounds discussed on this site.

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Human Chorionic Gonadotropin (HCG) is a glycoprotein compound typically supplied to research labs as a lyophilized powder sealed in a glass vial or cartridge. It requires reconstitution with an appropriate diluent before it can be drawn or handled in solution, and it is intended strictly for controlled laboratory use.

Once reconstituted, HCG solution is generally stored in a standard 3 ml glass cartridge and drawn using compatible injection hardware. Two hardware details are worth checking before setup:

• Pen needles: our reusable pens accept universal 28G-33G screw-on pen needles.
• Cartridge fit: Our pens take standard 3 ml (300-unit) glass cartridges with the 11 mm long plunger (stopper), the cartridge we sell. 3 ml cartridges are also made with a shorter, about 8 mm plunger, and a pen is built for one height, so check that a cartridge from another source has the 11 mm long plunger before loading it; the glass looks identical from the outside.

Confirming stopper length before reconstitution avoids mid-workflow surprises in the lab.

What it is

HCG (human chorionic gonadotropin) is a protein hormone belonging to the gonadotropin family, a group of hormones that act on the reproductive system. It occurs naturally in the placenta and is structured as two subunits joined together: an alpha subunit and a beta subunit, like two puzzle pieces forming one molecule. As a two-chain glycoprotein, HCG is structurally larger and more complex than many short-chain peptides.

The alpha subunit shares its structure with the alpha subunit found in LH and FSH, two related hormones produced by the pituitary gland. The beta subunit is unique to HCG - it is this piece that defines the hormone's distinct identity and the signal it carries. This alpha/beta pairing is characteristic of the gonadotropin family, though each hormone's beta subunit gives it a distinct, non-interchangeable signal.

Handling note: HCG is a delicate protein hormone. On the bench, reconstituted material should be handled gently, never shaken, and stored refrigerated at 2-8°C to help preserve structural integrity for research use.

Research context and categorization

HCG is categorized within reproductive and endocrine (hormone system) research. Its molecular activity closely resembles luteinizing hormone (LH), which is why studies group it with signaling pathways between the brain and reproductive organs in both sexes. This classification places HCG alongside other gonadotropins referenced in hormone receptor research, distinct from metabolic peptides studied in unrelated categories.

Research Applications

• Female-focused models: studied for its role in triggering the final stages of egg development and ovulation, including work tied to assisted-reproduction protocols.
• Male-focused models: investigated for how it prompts testicular steroid hormone production, along with its relationship to endogenous testosterone signaling and sperm production support.
• Pediatric endocrinology models: referenced in research on non-obstructive cryptorchidism (undescended testicles before puberty).

Weight Regulation Claims

HCG has a long history of marketing tied to weight loss. Regulatory review, including statements from the FDA, has found no solid evidence supporting that use, and the FDA has specifically warned against over-the-counter HCG products sold on that basis. This use category remains unconfirmed and falls outside any approved indication - a distinction relevant to how such research is classified and interpreted.

Status

Regulatory status

HCG is regulated as a prescription pharmaceutical product in the United States. It is manufactured under pharmaceutical quality standards, requires prescriber oversight, and is distributed through licensed pharmacies rather than research suppliers. It is not sold or labeled as a research-only compound, and nothing in this reference implies otherwise.

Sport status

HCG appears on the WADA Prohibited List. Chorionic gonadotropin (CG) and luteinizing hormone (LH), along with substances that trigger their release, are classified under S2 (peptide hormones, growth factors, related substances and mimetics). This class is banned for males at all times, whether an athlete is currently competing or not, and the classification applies regardless of the substance's form or source.

Reconstitution notes (general)

HCG is usually supplied as a lyophilized powder (freeze-dried, similar to instant coffee) that must be mixed with bacteriostatic water before lab use. To find the final concentration, divide the total units in the vial by the milliliters of water added.

For example, a 5,000 IU vial mixed with 2 mL of water gives 2,500 IU per mL. A 10,000 IU vial mixed with 10 mL gives 1,000 IU per mL. Use the calculator at peptide calculator to figure out concentration from vial units and water volume.

Does benzyl alcohol affect stability in solution?

Bacteriostatic water contains a small amount of benzyl alcohol as a preservative, which is why it's used instead of plain sterile water for multi-draw vials. Once reconstituted, a lyophilized peptide is no longer in its stable freeze-dried state — temperature, light exposure, and time in solution can all affect how a mixed vial holds up. For that reason, reconstituted vials are typically stored refrigerated and used within a limited window rather than indefinitely.

Dilution and handling notes (compound-specific)

HCG reference material is measured in international units (IU), not milligrams. Vials are typically labeled 5,000 IU or 10,000 IU, and the amount of diluent added sets the working concentration of the resulting solution.

A commonly referenced ratio is roughly 1 mL of bacteriostatic water per 1,000 IU, meaning a full vial is usually reconstituted with somewhere between 2 mL and 10 mL of water depending on the target concentration.

Bacteriostatic water contains about 0.9 percent benzyl alcohol as a preservative, which limits bacterial growth in a vial that is stored and drawn from multiple times rather than used in one session. It is generally preferred over plain sterile water for exactly this reason.

Reconstitution and Mixing Technique

HCG powder typically dissolves without aggressive mixing. Standard technique is to direct the stream of diluent at the inner glass wall of the vial rather than onto the powder, then swirl gently until the solution clears. Aggressive shaking can introduce foam and mechanical stress to the protein structure, so gentle swirling is the standard reference approach.

Benzyl alcohol's preservative action is a separate property from solution stability over time. Published protein-stability literature notes that benzyl alcohol concentration, storage temperature, and repeated freeze-thaw cycles can each independently influence how long a reconstituted solution retains its structural integrity - benzyl alcohol itself is not a stabilizer against degradation, only against microbial contamination.

A properly mixed vial should appear clear and colorless. Cloudiness, discoloration, gel-like texture, or visible particulate are signs the solution has been compromised and reference material in that state should not be used for further work.

Handling and storage

• Store mixed solution refrigerated at 2 to 8 degrees Celsius, protected from direct light.
• Wipe the cartridge septum with alcohol before each draw, and record the reconstitution date on the label.
• As a general reference point, mixed solution is commonly used within about four weeks when refrigerated; potency can decline over time, with temperature exposure, and depending on the diluent used.
• Discard any vial or cartridge that has turned cloudy, changed color, or shows particles - these are visual signs the contents may no longer be stable.
• Unmixed freeze-dried powder is generally stored at normal room temperature until reconstitution, per the product's label instructions.
• Our pens take standard 3 ml (300-unit) glass cartridges with the 11 mm long plunger (stopper), the cartridge we sell. 3 ml cartridges are also made with a shorter, about 8 mm plunger, and a pen is built for one height, so check that a cartridge from another source has the 11 mm long plunger before loading it; the glass looks identical from the outside. Pens accept universal 28G-33G screw-on pen needles.

Frequently asked questions

More in our bacteriostatic water and diluents collection.