HCG — Human Chorionic Gonadotropin

About HCG

The heterodimeric glycoprotein hormone whose beta subunit underpins every modern pregnancy assay.

Human chorionic gonadotropin is a heterodimeric glycoprotein of 237 amino acids across two subunits. The alpha subunit is shared with LH, FSH and TSH; the beta subunit is unique to hCG and is what every pregnancy test on the market actually detects.

Because its beta subunit is so distinctive and its structure so heavily glycosylated, hCG occupies an unusual position in endocrinology — simultaneously a diagnostic marker, a tumour marker, and a functional LH-receptor agonist. That triple role is why it appears across such a wide span of the research literature.

Research mechanism

hCG research centres on:

• LH/CG receptor agonism — hCG binds the same receptor as luteinising hormone, with a substantially longer half-life
• Gonadal steroidogenesis — Leydig-cell testosterone and ovarian progesterone production models
• Corpus luteum maintenance — the mechanism underlying its role in early pregnancy
• Beta-subunit immunoassay — the analytical basis of pregnancy and tumour-marker testing
• Glycosylation variants — hyperglycosylated hCG and its distinct receptor behaviour