hCG (human chorionic gonadotropin)

1 Identity

Heterodimeric glycoprotein hormone, alpha and beta subunits, heavily and heterogeneously glycosylated. Not A peptide, and since 23 March 2020 a licensed biological product. The marketed urinary article is purified from human pregnancy urine. Ovidrel and choriogonadotropin alfa (the recombinant article, a different manufacturing origin). Not a synonym and not this article: gonadorelin.

Sequence

Not a defined short peptide, and no sequence is written on this record as a specification. Per the FDA-approved labeling, hCG "is a polypeptide hormone produced by the human placenta", composed of alpha and beta subunits, where "the alpha sub-unit is essentially identical to the alpha sub-units of the human pituitary gonadotropins" (LH, FSH and TSH), with biological specificity residing in the beta subunit; the marketed urinary product is "obtained from the human pregnancy urine" (Chorionic Gonadotropin labeling, Fresenius Kabi, DailyMed SetID f93b2baa-03ac-4650-b35a-20b818d712d6, published 21 April 2025). The mature alpha subunit is 92 amino acids and the mature beta subunit is 145, so the assembled heterodimer is 237 residues — comfortably past the 40-amino-acid threshold that made it a "protein" in the 2020 biologics transition. Both subunits carry N-linked glycans and the beta subunit additionally carries O-linked glycans; the carbohydrate is roughly a third of the mass, is heterogeneous between molecules and between lots, and is not a contaminant but part of the article.

Molecular formula

Not applicable, and this is a property of the article rather than a gap in the research. A glycosylated heterodimeric protein with heterogeneous carbohydrate content has no single molecular formula. No formula is stated here and none should ever appear on a certificate for this article.

Average mass

Not established, and deliberately not printed as a single number. Approximately 37 kDa is the figure usually quoted for intact glycosylated hCG, and the FDA label states no molecular weight. No figure is established here either, and none is constructed, because the quantity does not exist as a scalar: glycoform heterogeneity spreads the intact mass across a distribution whose width is a lot property. The only honest specifications for this article are a deconvoluted intact-mass distribution with a defined acceptance window, plus separate subunit and released-glycan analyses — and, in the market, potency in International Units rather than in mass at all. Because the article is specified in International Units of biological activity rather than in milligrams, no mass-based certificate can be written for it, and a vial labeled only in International Units cannot be released against a chemistry specification at all.

Monoisotopic mass

Not established and not computable. A monoisotopic mass is meaningful only for a molecule of defined elemental composition; a heterogeneously glycosylated 37 kDa heterodimer has none, and at that mass the isotope envelope is not resolved by the instruments this channel uses in any event. Printing a monoisotopic figure for hCG would be the exact failure mode this catalog exists to prevent: a number that looks authoritative and refers to nothing.

Salt / variant note

The variants that matter here are manufacturing origins and unit systems rather than masses, because there is no mass to vary. (1) URINARY-derived hCG, purified from pooled human pregnancy urine — the marketed article under BLA017067 and the form the gray channel ships. Composition is a distribution of glycoforms and the article is specified in international units of biological activity, not in milligrams, which means no mass specification is possible and no mass-based certificate can be written for it. (2) recombinant choriogonadotropin alfa (Ovidrel) — a different manufacturing origin, a different license, a narrower and better-controlled glycoform distribution, and still a licensed biologic. (3) Free alpha subunit, 92 residues, which is common to hCG, LH, FSH and TSH and therefore establishes nothing about identity on its own; free beta subunit, 145 residues, where the specificity resides. A preparation assayed only on the alpha subunit has not identified hCG. (4) Nicked hCG and hCG beta core fragment — the recognized degradation and metabolite forms, both immunoreactive in some assay formats, which is why an immunoassay result alone is not an identity test. (5) animal-origin chorionic gonadotropins, including equine chorionic gonadotropin (PMSG). These are cheap, are widely available in the veterinary and research channels, and are the substitution to expect against an hCG order; they are not the approved human product and they are not this article. (6) "Homeopathic" and over-the-counter hCG products: DailyMed still carries a stratum of 2011-era listings under names such as "Homeopathic HCG formula", "HCG with slimming HERBS" and "E-HCG fat release system". Those are historical listing artifacts and are not this article. (7) The commonest presentation in the gray channel is a vial labeled in International Units — 5,000 IU is the modal figure — with no protein content, no glycoform data and no source declaration.

2 Class & testing panel

Form

Single article

Testing panel

P4 — panel definitionP4 is assigned as the closest fit for a protein article, and it fits the recombinant form. For the urinary-derived form, which is what the gray channel actually ships, the honest panel is P7, because a purified mixture of glycoforms from a pooled human biological fluid has no single defined composition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists and the index grades it A: multiple adequately powered human randomized controlled trials, with the grade expressly confined to the approved indications. Regulatory documents are the primary evidence on this record. FDA-approved labeling, Chorionic Gonadotropin, Fresenius Kabi, DailyMed SetID f93b2baa-03ac-4650-b35a-20b818d712d6, published 21 April 2025, sets out three approved indications. The approved labeling for that product is the reference document for its identity; its indications are a matter for that product and are not reproduced here.

4 Storage & specification

Storage

Sealed original container, held at -20 degrees C plus or minus 5 degrees C for routine stock and at -80 degrees C for long-term retention, desiccated and protected from light. The article is a heterogeneously glycosylated heterodimer, so the conditions are written against physical failure rather than against a single chemical degradant: freeze-thaw cycling is a named parameter, solutions are aliquoted single-use, and low-concentration work is done in low-binding labware. Incoming material is quarantined on receipt and is released against an identity result that resolves the assembled heterodimer from free alpha subunit, free beta subunit, nicked hCG and the beta core fragment, because an immunoassay result alone is not an identity test.

Shelf life

Dated from QA release, with a printed retest date on every unit and first-expiry-first-out enforced against that date. The interval is set on this company's own stability data rather than inherited from a supplier's certificate. The dating attributes are the ones this article actually has: potency in International Units, the deconvoluted intact-mass distribution against its defined acceptance window, the separate subunit and released-glycan profiles, aggregation, the nicked and beta-core forms, and water content. A single mass-based content figure is not among them, because a heterogeneously glycosylated heterodimer has no one defined composition to assay against.