What Is HMG?

Published September 2026 · Patriot Labs Research Team · ~12 min read

A menopausal-urine hormone, borrowed by the laboratory

Most of the compounds in this catalogue are small synthetic chains a few residues long, assembled on a machine to an exact sequence. HMG is the opposite of that in almost every way. It is not synthesized, it is extracted — historically from the pooled urine of postmenopausal women — and it is not one substance but a mixture of glycoprotein hormones. The two activities it is prized for are the two gonadotropins: follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the pair of pituitary signals that sit at the bottom of the hypothalamic–pituitary–gonadal (HPG) axis and drive the gonads. A standard vial of menotropins is described by a pair of numbers rather than a molecular formula: characteristically 75 IU of FSH activity together with 75 IU of LH activity, a roughly one-to-one balance of the two arms.¹

Why does a fertility preparation with that pedigree sit in a research-peptide catalogue at all? For the same reason HCG does: the receptors. Menotropins engage the FSH receptor and the LH/choriogonadotropin receptor — the two receptor systems that reproductive endocrinology uses to study follicular development, gonadal steroid synthesis, and the coordination of the reproductive axis. Because a single preparation delivers both signals at once, it became, decades ago, a convenient standard stimulus for probing gonadotropin biology in cells and animal models. That is the thread that runs through the whole story: HMG is studied less as a molecule in its own right — it is not one — than as a well-characterized, dual-activity tool. To place it in the wider family the catalogue carries, the site’s overview of what peptides are is the natural starting point, and its guide to the HPG-axis peptides sets menotropins beside the upstream signals they are most often studied alongside.

A mixture, not a molecule: two activities in one vial

The single most important thing to understand about HMG is that it has no one structure to draw. Where a guide to a synthetic peptide can put a sequence on the page, menotropins can only be described as a defined biological preparation: a purified extract standardized to deliver a stated amount of each of two activities. The active players belong to the glycoprotein hormone family — the same small club of heterodimeric, heavily sugar-coated hormones that includes FSH, LH, HCG, and TSH, each built from a shared alpha subunit and a distinguishing beta subunit. Everything the HCG guide says about that two-subunit architecture and its glycosylation applies to the gonadotropins in HMG as well; the difference is simply that HMG carries more than one of them.

The two arms do different jobs, which is exactly why the combination is interesting. FSH activity acts on the cells that support gamete development. LH activity acts on the cells that make steroid hormones. In the classic account of ovarian function — the “two-cell, two-gonadotropin” model — those two signals have to work together: LH drives the theca cells to produce androgens, and FSH drives the neighbouring granulosa cells to convert those androgens into estrogens. A preparation that supplies both at once is, in effect, a bottled version of that cooperative signal, which is a large part of why menotropins have been such a durable research and clinical material. The catalogue also carries single-arm relatives for contrast — the growth-hormone-axis secretagogues such as Tesamorelin and CJC-1295 operate on a completely different axis — but within the reproductive axis, HMG is distinctive precisely for carrying two signals in one vial.

The LH activity that is really hCG

Here is the detail that makes HMG genuinely fascinating on the bench, and it is the sort of thing that only surfaces when analytical chemists take a preparation apart. When modern highly purified HMG (the grade sold as Menopur, and studied under the label HP-hMG) is examined closely, the “LH” activity turns out to be almost entirely hCG, not luteinizing hormone.² The reason is a quirk of the raw material. Urinary LH is comparatively fragile and is preferentially lost as a preparation is purified, so as menotropins are refined toward higher purity, the genuine LH content falls away. To keep the labelled one-to-one FSH:LH balance, the LH-like bioactivity is supplied by chorionic gonadotropin — the closely related hormone that binds the very same receptor and is far more stable.

The analytical picture is striking. Detailed profiling of purified menotropin preparations has repeatedly found the LH beta subunit present only in traces — on the order of one percent — while the hCG beta subunit is present in far larger amounts.² Earlier work reached the same conclusion from different angles: one study measured roughly ten times more hCG than LH by content, and another concluded that about 95 percent of the LH bioactivity in highly purified HMG was contributed by hCG rather than by luteinizing hormone.³ In other words, the molecule that the HCG guide describes at length is not just a cousin of HMG — it is, in the purified product, the material that actually carries one of HMG’s two headline activities. It is a clean illustration of a theme the site returns to often: the name on the label is a claim about activity, and it takes analytics to reveal which molecules are really doing the work. The site’s guide to reading a certificate of analysis makes exactly this general point.

hMG, menotropin, HP-hMG: sorting the labels

Search for this material and the terminology multiplies, so it helps to sort the labels. HMG and hMG both stand for human menopausal gonadotropin, the descriptive name that records where the material came from. Menotropins is the formal pharmacopeial and generic name for the same class — the word you will see in an official monograph. HP-hMG or highly purified HMG refers to the modern, low-protein grade in which most of the non-gonadotropin urinary proteins have been stripped away and the LH activity is standardized with hCG, as described above.

Layered on top of the generic names is a long list of brand names that different manufacturers have used over the decades — Pergonal, the original; and later products including Menopur, Repronex, Menogon, Merional, Humegon, and others.¹ These are not different molecules so much as different preparations and purity grades of the same menotropin idea. It is worth keeping the family straight, because a study or a certificate that refers to “HP-hMG” is describing a more defined material than one that simply says “hMG,” and the two are not automatically interchangeable when precise composition matters.

From 1949 postmenopausal urine to the recombinant era

HMG has one of the oddest and best-documented origin stories in all of endocrinology, and it begins with a simple physiological fact. After menopause, the ovaries stop responding to the pituitary, and the negative feedback that normally restrains the gonadotropins is lost — so FSH and LH levels rise sharply, and the body excretes them in the urine. Postmenopausal urine, in other words, is an unusually rich natural source of gonadotropins. In 1949, the Italian chemist Piero Donini, working at the pharmaceutical company Serono, developed a relatively simple method to extract those gonadotropins from postmenopausal urine, producing the first practical menotropin material.⁴ Roughly a decade later, in 1961, the preparation was successfully introduced into clinical study by the reproductive endocrinologist Bruno Lunenfeld, and the first pregnancies attributed to menotropin stimulation followed shortly after.⁴

The part of the story that people remember, though, is the logistics. Because the raw material was human urine, and because the yield per litre was small, producing menotropins at scale meant collecting enormous volumes of it. The widely recounted history holds that Serono — whose leadership had connections in Italy that reached, by some accounts, to the Vatican — organized large-scale collection from postmenopausal women, including from communities of retired nuns, to feed early production.⁵ Whatever the precise details of that much-retold anecdote, the underlying point is real: for most of the twentieth century, menotropins were an extraction product of pooled human urine, and the early material was far from pure — the gonadotropins made up only a small percentage of the total protein, the rest being a long tail of other urinary constituents.

That impurity drove the entire arc of the field’s development. Over the following decades the preparations were progressively refined: from crude menotropins, to purified urinary FSH (urofollitropin, in which the LH activity was largely removed), to the highly purified HMG of today with its hCG-standardized LH activity. The modern chapter arrived with recombinant gonadotropins — follitropin alfa and beta for FSH, and lutropin alfa for LH, produced in cultured mammalian cells rather than harvested from urine — which offered defined, batch-consistent alternatives to the extracted material. The journey from a barrel of urine in 1949 to a recombinant glycoprotein in a bioreactor is a compact history of twentieth-century reproductive endocrinology, and it is a completely different manufacturing arc from the one described in the site’s account of how peptides are made, because a glycoprotein hormone cannot be built by solid-phase synthesis at all — it has to be either expressed by living cells or extracted from a biological source that already made it.

The pathways the studies point to

Because HMG carries two activities, it engages two receptors, and both belong to the same broad class of G-protein-coupled receptors. The FSH receptor (FSHR) sits on the supporting cells of the gonads — the granulosa cells of the ovarian follicle and the Sertoli cells of the testis. The LH/choriogonadotropin receptor (LHCGR) — the same receptor described in the HCG guide — sits on the steroid-producing cells: the ovarian theca and luteal cells and the testicular Leydig cells. When a gonadotropin binds, the receptor’s principal move is to couple to the Gs protein and switch on adenylyl cyclase, raising intracellular cyclic AMP (cAMP) and activating protein kinase A (PKA), the cascade that turns up each cell’s specialized machinery.

What makes the combined preparation conceptually neat is that the two arms map directly onto the two-cell, two-gonadotropin model. In that model, LH-driven signalling in the theca cell produces androgens; FSH-driven signalling in the neighbouring granulosa cell switches on the enzyme aromatase, which converts those androgens into estrogens; and FSH also supports the growth and maturation of the follicle itself. Neither signal alone reproduces the full picture — the androgen substrate and the aromatase have to be supplied by different cells responding to different gonadotropins — which is precisely why a preparation that delivers both FSH and LH activity in one has been such a useful research stimulus for studying folliculogenesis and gonadal steroidogenesis. In the male-oriented models the logic is parallel: FSH activity is studied at the Sertoli cell for its role in supporting spermatogenesis, and LH activity at the Leydig cell for androgen production. Set against the upstream signals, HMG acts at the very bottom of the axis: where Kisspeptin-10 acts high in the brain to trigger GnRH release and set the whole cascade in motion, menotropins stand in for the pituitary gonadotropins that are the axis’s final output to the gonad.

The research record

By the standards of this catalogue, menotropins are exceptionally well studied — they are among the oldest gonadotropin preparations in continuous use, with more than sixty years of literature behind them. Much of that literature is comparative: because urinary menotropins and the newer recombinant gonadotropins occupy the same niche, a large body of controlled work has set highly purified HMG against recombinant FSH, and recombinant-FSH-plus-LH regimens, in reproductive-endocrine research. The reason those comparisons remain interesting is the hCG detail above — a urinary preparation whose LH activity is carried by hCG is not molecularly identical to a recombinant FSH/LH combination, so the two can behave differently, and untangling why has been a productive research question in its own right.

The important caveat is about what that literature is about. The overwhelming majority of the human record on menotropins concerns their use as approved medicines within reproductive medicine — studied in patients, under medical supervision, in tightly controlled clinical settings. A deep clinical evidence base for a gonadotropin preparation is not the same thing as evidence for what a research-grade material does for any individual outside that setting, and the two should never be conflated. Results in the comparative literature also vary by endpoint and population, which is why the honest description of HMG is as a research material rather than a product with a settled superiority claim. The table below summarizes what the record establishes and where its edges are.

An approved biologic, not a research peptide

Like HCG, menotropins sit in a different regulatory bucket from most of the catalogue, and the distinction is worth stating precisely. Research-associated peptides sold outside the approved-drug system have drawn growing FDA attention, and on July 23–24, 2026 the agency’s Pharmacy Compounding Advisory Committee met to review a slate of seven peptides as candidates for the 503A bulk drug substances list that governs what licensed pharmacies may compound. Those seven were BPC-157, KPV, TB-500, MOTS-c, emideltide (DSIP), Epitalon, and Semax.⁶ Menotropins were not on that list — and the reason they were not is instructive.

Each of those seven is a relatively novel peptide without a long-standing US approved-drug pathway; that is exactly why a compounding committee was weighing whether pharmacies could prepare them at all. HMG is the opposite case. It is a long-approved gonadotropin preparation, the active material in prescription fertility medicines that have been on the market for decades — the original Pergonal and the modern highly purified products such as Menopur and Repronex — with recognized pharmacopeial standards and WHO International Standards behind its potency.^1,7 A material with that pedigree simply was not the kind of substance the July 2026 review was convened to examine. That fact does two things at once: it explains why HMG sits in a different regulatory category from the research peptides beside it, and it makes the research-use framing more important rather than less.

Because none of that approved-drug history describes the footing on which a research supplier operates. The existence of approved medicines containing menotropins is a fact about those specific, regulated products, prescribed and dispensed through the healthcare system. Research-grade HMG is a separate thing: laboratory material, characterized for identity and potency, and sold for in-vitro research use only. The site’s guide to how peptides differ from drugs and biologics covers exactly why an approved biologic, a compounded preparation, and a research chemical are three different categories even when the underlying molecules overlap — a distinction that menotropins, as an approved biologic offered here strictly as research material, illustrate about as clearly as any entry in the catalogue.

Bench practice: characterizing a gonadotropin mixture

Characterizing menotropins is a genuinely different exercise from characterizing a short synthetic peptide, and the difference comes straight from the chemistry above. A small peptide has one exact mass and a single sequence, so a mass-spectrometry reading and a purity number from reversed-phase HPLC settle its identity. HMG has neither luxury. It is a mixture of large glycoproteins whose sugars vary from molecule to molecule, in which the active components make up only a fraction of the total protein — so there is no single tidy mass to report, and “how much is in the vial” is a question about activity, not weight.

That is why gonadotropin potency is expressed in International Units (IU) rather than milligrams. The active gonadotropins have extremely high specific activity — recombinant FSH runs in the thousands of IU per milligram and hCG higher still — so a difference of nanograms in protein content corresponds to a meaningful difference in biological activity, and a mass figure alone would be almost useless as a measure of strength.⁸ Historically, potency has been assigned by in-vivo bioassay against a common reference: FSH activity by the classic Steelman-Pohley assay, which reads out the increase in ovarian weight of immature rats primed with hCG, and LH activity by the rat seminal-vesicle or ventral-prostate weight-gain assay. Those bioassays are inherently variable — coefficients of variation on the order of 10 to 20 percent are typical, so a nominal 100 IU can read anywhere from roughly 80 to 120 — which is one reason each preparation is calibrated to a WHO International Standard so that a unit measured in one laboratory means the same thing in another.⁸ More modern characterization supplements the animal assays with immunoassays that distinguish the individual subunits, mass spectrometry, and dedicated reversed-phase HPLC methods that quantify the shared alpha subunit and the FSH-specific beta subunit and report purity by area — the analytical tools that let a laboratory confirm which gonadotropins, and how much of each activity, a given lot actually contains.

Storage follows the general rules for the class, with the usual glycoprotein caveats. Research-grade HMG is supplied as a lyophilised (freeze-dried) solid, and as a dry powder kept cool, sealed, dry, and protected from light it is comparatively stable; once reconstituted it is far more vulnerable, and protection from repeated freeze–thaw cycling and from microbial contamination becomes the practical concern, since large folded proteins are more easily damaged by rough handling than a short peptide is. The site’s storage guide covers the practical handling and its COA explainer covers what a credible certificate should show; none of that is a use instruction, only the analytical hygiene that lets a laboratory trust that what is in the vial matches the label.

What the evidence does not establish

Menotropins carry more clinical baggage than almost any material on this list, and the honest move is to draw the boundary plainly. The biology is real and deeply documented, and the role of gonadotropins in reproductive medicine is a matter of settled science. But that record describes a set of regulated medical products used under supervision; it does not describe, and should not be read as describing, what a research-grade preparation does for any person. Nothing in the structural, mechanistic, or historical account above is a claim about outcomes, and none of it is a use instruction.

Two further limits are worth naming. First, HMG is a variable biological mixture, not a defined molecule, and the analytical work above — the traces of real LH, the hCG that carries the LH activity, the long tail of urinary proteins in less-purified grades — is a reminder that “HMG” names an activity profile rather than an exact structure. Second, the large clinical literature is comparative and endpoint-dependent, so it supports no blanket claim of superiority over other gonadotropin preparations. A research audience is best served by regarding menotropins for what they are on the bench: a historically important, dual-activity gonadotropin preparation, standardized in International Units and useful precisely because its composition and receptor targets are so thoroughly mapped. For placing it against the molecules it shares an axis with, the guide to HPG-axis peptides and the HCG explainer are the honest reference points.

The honest summary is that HMG is a urine-derived mixture of glycoprotein hormones carrying FSH and LH activity — the latter largely supplied by hCG — with more than seventy years of biology behind it, two clearly defined receptor targets, and a place in this catalogue as an approved biologic offered strictly as research material. That combination is exactly what makes it a legitimate subject for laboratory investigation, and exactly why it belongs in a research setting and nowhere else.

Frequently asked questions

Is HMG actually a peptide?

Not in the sense that most of the catalogue is, and not even in the sense that a single hormone is. HMG is not one molecule at all. It is menotropins: a mixture of glycoprotein hormones purified from human urine, carrying both follicle-stimulating-hormone (FSH) activity and luteinizing-hormone (LH) activity together, alongside other urinary proteins. Each active component is a large, sugar-coated glycoprotein of the same family as HCG, not a short synthetic chain assembled on a peptide synthesizer such as BPC-157. It is grouped with the peptides because it belongs to the same broad world of signaling molecules and is studied with overlapping tools, but it is better thought of as a standardized biological preparation than as a defined peptide.

What is the difference between HMG and HCG?

HCG is a single, defined glycoprotein hormone that acts as a luteinizing-hormone mimetic at one receptor, the LH/choriogonadotropin receptor. HMG is a mixture, and its defining feature is that it carries two activities at once: FSH activity, which engages the separate FSH receptor, plus LH-like activity. The twist is that in modern highly purified HMG the LH activity is not really luteinizing hormone at all. Urinary LH is fragile and is largely lost during purification, so analytical work has shown that the great majority of the LH-like bioactivity in preparations such as Menopur is actually supplied by hCG. In that sense HMG contains, and is partly standardized with, the very molecule described in the HCG guide.

Why is HMG measured in International Units instead of milligrams?

Because a milligram figure would not tell you what the material does. HMG is a heterogeneous mixture in which the active gonadotropins have extremely high specific activity and make up only a small fraction of the total protein, so a tiny difference in mass corresponds to a large difference in biological activity. For that reason gonadotropin potency is defined by bioassay against a common reference and expressed in International Units (IU). FSH activity is measured historically by the Steelman-Pohley assay, which reads out the ovarian-weight gain of immature rats, and LH activity by the rat seminal-vesicle or ventral-prostate assay, each calibrated to a WHO International Standard so that a unit measured in one laboratory means the same thing in another.

Was HMG part of the July 2026 FDA peptide compounding review?

No. On July 23 and 24, 2026 the FDA’s Pharmacy Compounding Advisory Committee reviewed seven peptides as candidates for the 503A bulk drug substances list: BPC-157, KPV, TB-500, MOTS-c, emideltide (DSIP), Epitalon, and Semax. Menotropins were not among them, and they sit in a different regulatory category from those substances. Where each of those seven is a novel peptide without a long-standing US approved-drug pathway, HMG is a decades-old, long-approved gonadotropin preparation with recognized pharmacopeial standards behind its potency. The compounding review concerned whether licensed pharmacies could prepare those specific research-associated peptides; it did not touch menotropins, whose status as an approved substance was never the question.

Is HMG intended for human use?

No. HMG supplied by Patriot Labs is sold strictly for in-vitro research and laboratory use only. It is not for human or veterinary consumption, and nothing in this guide describes how to administer it. Approved medicines that contain menotropins are separate, nationally regulated products prescribed and dispensed through the healthcare system; research-grade HMG is a laboratory material characterized for identity and potency, and that is the only footing on which it is offered here. For the practical side of sourcing verified material, see the guide on storing research peptides and the COA explainer.

References

All Patriot Labs products are sold strictly for in-vitro research and laboratory use only. Not for human or veterinary consumption. This guide is educational and describes gonadotropin chemistry and published research in general terms; it is not medical advice, does not describe how to use any product, and the references cited do not constitute a product claim.