What is HCG?
HCG (Human Chorionic Gonadotropin) is a glycoprotein hormone produced naturally by trophoblastic cells of the placenta during early pregnancy. Structurally it is a heterodimer of two non-covalently associated subunits: an α-subunit (92 amino acids, shared with LH, FSH and TSH) and a unique β-subunit (145 amino acids) which confers receptor specificity. Heavy N- and O-linked glycosylation gives the mature molecule a molecular weight of approximately 36,700 g/mol and is essential for its long circulating half-life.
HCG binds the luteinizing-hormone / chorionic gonadotropin receptor (LHCGR), a class-A G-protein-coupled receptor expressed on testicular Leydig cells and ovarian theca and granulosa cells. Receptor activation triggers Gs-coupled adenylyl cyclase / cAMP / PKA signalling, the canonical pathway by which the compound is studied in steroidogenesis and gonadal-axis research.
ClaraScience supplies HCG as a lyophilised powder in 5000iu vials, calibrated against the WHO International Standard for potency. Each batch is supplied at USP grade with a full Certificate of Analysis including potency assay and identity confirmation. All products are supplied for laboratory research use only.
Mechanism. LHCGR agonism on gonadal steroidogenic cells → Gs / cAMP / PKA cascade — mimics endogenous LH pulse pharmacology.
Structure. α-subunit 92 aa + β-subunit 145 aa · heavily glycosylated heterodimer · ~36.7 kDa.
Research context. Reproductive endocrinology, steroidogenesis pathway research, HPG-axis modulation models.
Research Background
HCG was first isolated from the urine of pregnant women in 1927, making it one of the longest-studied protein hormones in modern endocrinology. The foundational receptor pharmacology work by Catt and Dufau in the 1970s established HCG and LH as the two endogenous ligands of the same gonadal receptor (now designated LHCGR), with HCG distinguished by its substantially longer plasma half-life owing to heavier glycosylation.
The comprehensive review by Cole (2009, Reprod Biol Endocrinol) catalogues the structural biology and the distinct hyperglycosylated isoforms of HCG that have been characterised in pregnancy, malignancy and reproductive-research contexts. More recent work has explored HCG-driven testicular Leydig-cell steroidogenesis in HPG-axis suppression and recovery research models, and ovarian follicular maturation in IVF-adjacent research literature.
Because HCG's biological potency depends on its glycosylation pattern (which varies between source preparations), all serious research-grade HCG is calibrated against the WHO International Standard and reported in International Units (IU) rather than mass — a critical consideration when comparing data across studies and suppliers.
HCG is commonly studied alongside other HPG-axis modulators and growth-hormone-axis peptides such as Ipamorelin and CJC-1295 in receptor-pharmacology research.
Key citation Cole LA. "New discoveries on the biology and detection of human chorionic gonadotropin." Reprod Biol Endocrinol. 2009;7:8.
Compound Specifications
| Common Name |
HCG (Human Chorionic Gonadotropin) |
| Structure |
α-subunit 92 aa + β-subunit 145 aa · glycoprotein heterodimer |
| Molecular Weight |
~36,700 g/mol (glycosylated) |
| Receptor Target |
LHCGR (luteinizing-hormone / chorionic-gonadotropin receptor) |
| Grade / Potency |
USP · calibrated against WHO International Standard |
| Vial Size |
5000iu lyophilised powder |
| Storage |
2–8°C unopened · Reconstituted: use within 30 days |
| Primary Reference |
Cole LA, Reprod Biol Endocrinol 2009;7:8 |
Storage & Handling
HCG is supplied as a lyophilised powder in sealed vials. ClaraScience ships all orders in plain, discreet packaging from our Australian warehouse.
- Unopened vial: 2–8°C (refrigerated). Protein-based hormone — do NOT freeze the lyophilised vial as repeated freeze-thaw cycles can degrade glycoprotein activity.
- After reconstitution: Store at 2–8°C and use within 30 days. Do not freeze the reconstituted solution.
- Reconstitution solvent: Sterile bacteriostatic water. Reconstitute by gentle swirling — do not shake (mechanical shear can denature glycoprotein hormones).
Full protocols in our Storage & Handling Guide.
Ordering & Pricing — Australia
| Quantity |
Price per vial |
Saving |
| 1–4 vials |
$89.95 AUD |
— |
| 5–9 vials |
$79.95 AUD |
Save 11% |
| 10+ vials |
$74.95 AUD |
Save 17% |
Free priority tracked shipping on orders over $250 AUD. Dispatched within 24 hours. For bulk orders, see our wholesale enquiry page.
Frequently Asked Questions
What is HCG?
HCG (Human Chorionic Gonadotropin) is a placental glycoprotein hormone heterodimer composed of α and β subunits. It binds the luteinizing-hormone / chorionic-gonadotropin receptor (LHCGR) on gonadal steroidogenic cells. All ClaraScience products are for laboratory research use only.
Why is HCG dosed in IU rather than mg?
Glycoprotein hormones have a biological potency that depends on their glycosylation pattern, which varies between source preparations. International Units (IU) are calibrated against the WHO International Standard so activity is comparable across batches and suppliers, regardless of mass. 5000iu is the most widely used research vial size in published literature.
What receptor does HCG activate?
HCG binds the LHCGR (luteinizing-hormone / chorionic-gonadotropin receptor) — a class-A G-protein-coupled receptor expressed on testicular Leydig cells and ovarian theca/granulosa cells. Activation drives Gs / adenylyl cyclase / cAMP / PKA signalling, which is the principal pathway studied in steroidogenesis research.
Is HCG available in Australia for research?
ClaraScience supplies research-grade HCG from an Australian warehouse. Products are for laboratory research use only and have not been evaluated by the TGA for therapeutic purposes in this context.
How should HCG be stored?
Lyophilised vials are stored at 2–8°C (refrigerated). Do NOT freeze the lyophilised vial — repeated freeze-thaw cycles can degrade glycoprotein activity. After reconstitution with bacteriostatic water, store at 2–8°C and use within 30 days. Reconstitute by gentle swirling, not shaking.
