LH

The anterior-pituitary gonadotropin that triggers ovulation and drives Leydig-cell testosterone production; its recombinant form, lutropin alfa (Luveris), was approved in the U.S. in 2004 but had that approval withdrawn in 2016, leaving hCG as the clinical LH-activity surrogate.

Also referenced as: Luteinizing Hormone, Lutropin, Lutropin Alfa, r-hLH, Luveris, Interstitial Cell-Stimulating Hormone

What is LH?

Luteinizing hormone is a heterodimeric glycoprotein hormone secreted by gonadotrope cells of the anterior pituitary. Like hCG, FSH, and TSH, it pairs the common 92-amino-acid alpha subunit with a hormone-specific beta subunit — 121 amino acids for LH — held together non-covalently, with N-linked (but, unlike hCG, no O-linked) glycosylation. It is a full-size glycoprotein produced recombinantly in mammalian cells or purified from tissue, not a synthetic peptide made by solid-phase chemistry.

In males, LH drives Leydig-cell testosterone production; in females, it supports theca-cell androgen output through the follicular phase, and the mid-cycle LH surge triggers ovulation and corpus luteum formation. It appears in the research-compound market mostly as a reference point rather than a product: standalone LH is rarely sold, its recombinant drug form (lutropin alfa, marketed as Luveris) no longer has a U.S. approval, and the LH-activity role in practice is filled almost entirely by hCG, its longer-lived sibling at the same receptor.

How it works

• LH/hCG receptor agonism — LH binds the lutropin/choriogonadotropin receptor (LHCGR), a class A G protein–coupled receptor on testicular Leydig cells and ovarian theca, granulosa, and luteal cells, coupling primarily to Gs and raising cAMP to drive steroidogenesis; without functional LHCGR signaling, ovulation does not occur and Leydig cells do not develop normally (Ascoli et al., Endocrine Reviews, 2002, 23(2):141–174)
• Two-cell, two-gonadotropin estrogen synthesis — during the follicular phase LH stimulates theca cells to secrete androgens, which granulosa-cell aromatase, under FSH drive, converts to estradiol. In 38 LH- and FSH-deficient anovulatory women given a fixed 150 IU/day of recombinant FSH, adding recombinant LH at 0, 25, 75, or 225 IU/day produced dose-related increases in estradiol and androstenedione, with 75 IU/day sufficient for optimal follicular development in the majority of patients and a minority requiring up to 225 IU/day (European Recombinant Human LH Study Group, Journal of Clinical Endocrinology & Metabolism, 1998, 83(5):1507–1514)
• Pulsatile output downstream of GnRH — LH secretion is driven by roughly hourly hypothalamic GnRH pulses; in the classic rhesus experiment, intermittent GnRH delivery at one pulse per hour reestablished gonadotropin secretion while continuous infusion failed to sustain it and desensitized the pituitary (Belchetz et al., Science, 1978, 202(4368):631–633). This pattern-dependence is why chronic GnRH agonist dosing suppresses LH rather than raising it
• Short-lived, and not identical to hCG — after intravenous dosing, recombinant human LH distributes with an initial half-life of about 1 hour and is eliminated with a terminal half-life of 10–12 hours, with total serum clearance around 1.7 L/h (le Cotonnec et al., Fertility and Sterility, 1998, 69(2):189–194); by the subcutaneous route the licensed product’s label put the mean terminal half-life at about 18 hours. The O-glycosylated C-terminal extension on hCG’s beta subunit — which LH’s beta subunit lacks — is what gives hCG its far longer persistence in circulation (Fares et al., PNAS, 1992, 89(10):4304–4308). The two hormones also signal differently at the shared receptor, with LH behaving as a partial, biased agonist relative to hCG on beta-arrestin recruitment and progesterone production in vitro (Riccetti et al., Scientific Reports, 2017, 7(1):940)

Research status

LH pharmacology is textbook endocrinology, but the compound’s regulatory story is unusual: a recombinant LH drug was approved in the United States and then un-approved without ever confirming clinical benefit.

A drug that came and went. FDA approved lutropin alfa (Luveris, NDA 021322) on October 8, 2004 under the accelerated approval regulations at 21 CFR part 314, subpart H, for concomitant administration with follitropin alfa (Gonal-f) to stimulate follicular development in infertile hypogonadotropic hypogonadal women with profound LH deficiency (LH < 1.2 IU/L). The label itself stated that a definitive effect on pregnancy in this population had not been demonstrated. The trial the company agreed to at the time of approval was never completed — EMD Serono told FDA it was not feasible to complete, first asking in April 2012 to withdraw the application voluntarily, then, after FDA directed it to the accelerated-approval withdrawal pathway instead, requesting withdrawal under 21 CFR 314.150(d) in July 2015. FDA withdrew approval of the NDA effective April 12, 2016, and its notice is blunt about the consequence: because the required study was meant to verify and describe clinical benefit, that benefit has not been confirmed and the drug “has not been established to be safe and effective.” Because the withdrawal predates the March 2020 transition of protein drugs to biologics licenses, no deemed-BLA exists either: the United States currently has no licensed standalone LH product.

Where LH activity survives clinically. In the U.S., labeled LH activity persists in menotropins — Menopur, the only menotropin with a current U.S. label, is standardized per vial to 75 IU of FSH activity plus 75 IU of LH activity, assigned by rat bioassay (seminal vesicle weight gain for LH) against the WHO Fourth International Standard, and its label notes that hCG is detected in the preparation — and in hCG itself, whose LHCGR agonism is the working substitute for LH across reproductive endocrinology. Europe kept what the U.S. gave up: lutropin alfa remains centrally authorized there, both alone as Luveris (authorized November 2000) and in fixed combination with follitropin alfa as Pergoveris (authorized June 2007).

The supplementation question in assisted reproduction. Whether adding recombinant LH to FSH improves IVF/ICSI outcomes has been tested extensively and remains unresolved. The 2017 Cochrane review pooled 36 randomized trials (8,125 women), but only four of them (499 women) reported live birth, where it found no clear difference (OR 1.32, 95% CI 0.85–2.06, very low-quality evidence), and six (2,178 women) reported ovarian hyperstimulation syndrome, again with no clear difference (OR 0.38, 95% CI 0.14–1.01, low-quality evidence). Against that sat moderate-quality evidence of a modest improvement in ongoing pregnancy rate (OR 1.20, 95% CI 1.01–1.42, 19 trials, 3,129 women). The authors concluded the evidence was insufficient to encourage or discourage the practice (Mochtar et al., Cochrane Database of Systematic Reviews, 2017, 5:CD005070).

A large randomized failure in the target population. ESPART, a Phase III single-blind active-comparator trial, randomized 939 poor ovarian responders — the group hypothesized most likely to benefit — to follitropin alfa/lutropin alfa or follitropin alfa alone. The primary endpoint showed no benefit: a mean 3.3 oocytes retrieved with the combination versus 3.6 with FSH alone, and live birth rates of 10.6% versus 11.7%. Post-hoc subgroup signals in moderate-to-severe poor responders, and a post-hoc reduction in total pregnancy outcome failure, were hypothesis-generating only — the trial was not powered for them (Humaidan et al., Human Reproduction, 2017, 32(3):544–555).

Trial registry picture. ClinicalTrials.gov lists roughly 81 studies with lutropin alfa as an intervention (August 2026), overwhelmingly female-fertility adjunct work — infertility, ovulation induction, IVF/ICSI stimulation — with a short tail of unrelated physiology studies. Male-axis work is close to absent, and the one entry that exists proves the point: a small investigator-initiated Phase II pharmacodynamics and safety study in 32 hypogonadotropic hypogonadal men comparing recombinant LH against urinary hCG, whose own rationale states that LH has not previously been used in men (NCT04189133, Azienda Ospedaliero-Universitaria di Modena; listed start 2022, status unknown). What the registry contains nothing of is the use that actually drives gray-market gonadotropin interest — LH alongside exogenous testosterone for testicular stimulation, or as endogenous-axis support. LH’s short half-life makes it impractical for that role, and the clinical evidence for it belongs to hCG.

Common dosage forms

• Former U.S. prescription form — Luveris was supplied as a lyophilized powder; each vial contained 82.5 IU of lutropin alfa and delivered 75 IU after reconstitution with 1 mL of sterile water, for subcutaneous injection. It is no longer marketed in the United States.
• European prescription forms — Luveris vials and Pergoveris, a fixed-ratio combination given at a recommended starting dose of 150 IU follitropin alfa with 75 IU lutropin alfa once daily.
• Menotropins (hMG) — Menopur, standardized to 75 IU FSH activity plus 75 IU LH activity per vial, is the only labeled LH activity in the American prescription market apart from hCG.
• Laboratory reagents — purified human pituitary LH sold by biochemical suppliers in microgram quantities for immunoassay calibration and receptor studies; a reagent channel, not a vialed research-injection product.
• Research-market listings — standalone “LH” vials are rare in research catalogs; listings that invoke LH usually turn out to be hCG, hMG, or upstream peptides such as gonadorelin or kisspeptin. Where LH itself is offered, potency belongs in bioassay International Units, not milligrams.

Key considerations

• There is no licensed U.S. reference product. Lutropin alfa’s approval was withdrawn in 2016 because the confirmatory study required under accelerated approval was never completed, and FDA’s own notice states the drug “has not been established to be safe and effective.” That is a statement about missing evidence rather than a finding of harm, but it is not a clean bill of health either, and it is worth resisting the softer telling in which the product simply stopped selling. Any product sold as LH today has no current U.S. label, potency standard enforcement, or licensed manufacturer behind it.
• hCG is the surrogate, not the same molecule. hCG hits the same receptor but circulates far longer and signals with a different bias profile; results and habits from hCG use do not translate one-to-one to LH, and vice versa. Recombinant LH’s terminal half-life is 10–12 hours intravenously and about 18 hours by the subcutaneous route the product actually used — short enough that Luveris required daily injection, and a principal reason it never displaced hCG.
• Potency is a bioassay quantity. LH activity requires correct alpha/beta heterodimer assembly and glycosylation, and the licensed product’s potency was assigned by in vivo bioassay — the Van Hell method described in the British Pharmacopoeia, run against a house standard calibrated to the relevant international standard. A mass-and-purity certificate of the kind issued for small synthetic peptides cannot establish that an LH vial has any particular biological activity.
• Naming confusions are everywhere. “LH” on a lab report is a diagnostic measurement, not a product; supplement-market “LH boosters” are herbal formulations containing no hormone; lutropin alfa, Luveris, and the lutropin alfa component of Pergoveris are the same recombinant molecule; and older literature calls LH interstitial cell-stimulating hormone in males.
• Class safety signals are documented. The Luveris label carried the gonadotropin class warnings — ovarian hyperstimulation syndrome, multiple births, and thromboembolic events in the context of ovarian stimulation — restricted use to women with profound LH deficiency, and directed that the drug be used only by physicians thoroughly familiar with infertility management. The absence of an approved U.S. product means no pharmacovigilance stream exists for any current gray-market use.