LH
The pituitary gonadotropin that drives testosterone synthesis in men and triggers ovulation in women.
LH (luteinizing hormone) is an endogenous heterodimeric glycoprotein hormone secreted by pituitary gonadotrophs. It shares a common alpha subunit with FSH, TSH, and hCG but carries a unique LH-beta subunit that is structurally homologous to hCG-beta. Through pulsatile release governed by hypothalamic GnRH, LH stimulates Leydig cell testosterone biosynthesis in men and produces the midcycle surge that triggers ovulation and supports luteal-phase progesterone in women. A recombinant form, lutropin alfa, is used clinically to supplement LH-deficient women undergoing assisted reproduction.
Class
Endogenous heterodimeric glycoprotein hormone (gonadotropin)
Routes
Subcutaneous, Intramuscular
Category
Hormone & Reproductive
Researched benefits
What it's studied for
Testosterone stimulation
In men, tonic LH binds LH receptors on testicular Leydig cells and drives the cholesterol-to-testosterone biosynthetic pathway via cAMP/StAR activation, making it the central upstream signal for endogenous testosterone production.
Ovulation induction
The midcycle LH surge triggers follicular rupture and corpus luteum formation, the defining event of ovulation in women.
Fertility support
Recombinant LH (lutropin alfa) can substitute for endogenous LH during controlled ovarian stimulation in gonadotropin-deficient women, supporting follicular development in assisted reproduction.
HPG axis support
As the pituitary output of the hypothalamic-pituitary-gonadal axis, LH integrates GnRH pulsatility with gonadal steroid output; recovery of normal LH levels marks restoration of gonadal axis function in conditions such as prolactinoma.
Estrogen precursor signaling
LH activates ovarian theca cells to synthesize androgens, which granulosa cells then aromatize to estrogen under FSH regulation, and it sustains luteal-phase progesterone production.
Mechanism
How it works
LH is a heterodimeric glycoprotein composed of a common alpha subunit (shared with FSH, TSH, and hCG) and a hormone-specific LH-beta subunit that is structurally homologous to hCG-beta. It is synthesized and released by pituitary gonadotrophs in a pulsatile pattern set by hypothalamic GnRH, and it signals through the LH receptor (LHR/LHCGR), which is also the receptor for hCG.
In men, tonic LH binds LH receptors on testicular Leydig cells and activates the cAMP/StAR pathway, stimulating the cholesterol-to-testosterone biosynthetic cascade. This makes LH the primary upstream driver of endogenous testosterone production.
In women, LH activates ovarian theca cells to produce androgens, which granulosa cells aromatize to estrogen under FSH regulation. The preovulatory LH surge then triggers follicular rupture (ovulation), formation of the corpus luteum, and luteal-phase progesterone secretion.
Because hCG binds the same receptor with a longer plasma half-life, hCG is commonly used clinically as an LH surrogate to trigger ovulation and support the luteal phase, while recombinant lutropin alfa is used to directly supplement LH in deficient patients.
Dosing protocols
Dosing & administration
Dosing reflects protocols reported in research and community literature for educational purposes. It is not medical advice or a recommendation. Most peptides here are not approved for human use.
ART / IVF supplementation (recombinant LH)
- Dose
- 75 IU/day lutropin alfa
- Frequency
- Daily during the stimulation phase
- Timing
- Added to recombinant FSH during the late follicular phase
- Duration
- Through controlled ovarian stimulation until the hCG trigger
- Route
- Subcutaneous
Regimen used in the Human Reproduction (2005) RCT adding recombinant LH to rFSH; clinical use is limited to physician-supervised assisted-reproduction settings in LH-deficient patients.
- LH is a clinical hormone product used under medical supervision, not a self-administered research peptide; dosing must be individualized by a fertility or endocrinology specialist.
- hCG is frequently substituted for LH clinically because it activates the same receptor with a longer half-life.
- No standardized recreational or performance dosing exists; only the ART supplementation regimen appears in the source evidence.
Evidence
Research & clinical studies (9)
The use of recombinant human LH (lutropin alfa) in the late stimulation phase of assisted reproduction cycles: a double-blind, randomized, prospective study
In 114 normo-ovulatory women undergoing IVF, adding recombinant LH (75 IU/day) to rFSH in the late follicular phase raised estradiol on the day of hCG but did not improve oocyte maturation, fertilization, pregnancy, or live birth rates.
PMID 16172149Recovery of gonadal axis in patients with prolactinomas
Cabergoline-treated prolactinoma patients showed recovery of the HPG axis with LH normalization over a mean of 82 days, influenced by baseline prolactin, sex, and age.
PMID 42214441Menopause and vascular endothelial health: Is it all about the oestrogen?
Rising LH and FSH during the menopause transition directly affect vascular endothelial health via oxidative stress, inflammation, and endothelin signaling, beyond estrogen decline alone.
PMID 42218087Pulsatile LH release in male and female Sprague Dawley and Wistar rats in different reproductive states
LH shows distinct pulsatile secretion patterns across the estrous cycle, gonadectomy, gestation, and lactation, supporting the rat as a model for HPG-axis study.
PMID 42215046Stress as a Neuroendocrine Modulator of the Reproductive Axis: Roles of Glucocorticoids, Kisspeptin and Serotonergic Signalling in Animal Models
Reviews how stress-related glucocorticoid, kisspeptin, and serotonergic signaling modulate the reproductive axis and gonadotropin output in animal models.
PMID 42371829Functional Landscape of Zebrafish Gonadotropins and Receptors: A Comprehensive Genetic Analysis
Comprehensive genetic analysis characterizes gonadotropin (including LH) and receptor function across zebrafish reproduction.
PMID 42376857Effect of recombinant human follicle-stimulating hormone or equine chorionic gonadotropin on the ovarian response in guinea pig
A synchronization protocol paired with recombinant human FSH/LH produced the highest corpora lutea counts and increased embryo recovery in guinea pigs.
PMID 42213185The effect of platelet-rich plasma extracellular vesicles (PRP-EVs) on the expression of BECN1, CYP19a1, and BMP6 in ovarian granulosa cells of a PCOS mouse model
PRP-derived extracellular vesicles altered autophagy and steroidogenesis gene expression in granulosa cells of a PCOS mouse model.
PMID 42372500Revisiting ESR in PCOS: an easily obtainable link to immune and metabolic dysregulation
Examines erythrocyte sedimentation rate as an accessible marker linking immune and metabolic dysregulation in PCOS, a condition characterized by altered LH signaling.
PMID 42374565Combinations
Stacking & blends
LH + FSH (co-stimulation)
Complete gonadotropin support for follicular development
LH drives theca-cell androgen synthesis while FSH drives granulosa-cell aromatization to estrogen; the co-formulation Pergoveris combines both to stimulate follicular development in LH-deficient women.
Safety
Side effects & considerations
Contraindications & cautions
- Active or prior cancer history
- Thyroid conditions
- Pregnancy or nursing
LH has a moderate risk profile in research and clinical contexts. It should only be used under the supervision of a qualified fertility or endocrinology professional, and contraindications should be reviewed before any use.
FAQ
LH — common questions
What is LH?
LH (luteinizing hormone) is an endogenous heterodimeric glycoprotein hormone produced by pituitary gonadotrophs. It shares a common alpha subunit with FSH, TSH, and hCG and carries a unique LH-beta subunit. LH drives sex-steroid synthesis through pulsatile, GnRH-regulated release, triggers ovulation via the midcycle surge in women, and sustains Leydig cell testosterone production in men.
What is LH primarily studied for?
Testosterone stimulation, fertility support, HPG-axis support, ovulation induction, and Leydig cell activation.
How does LH work in men versus women?
In men, tonic LH stimulates testicular Leydig cells to produce testosterone via the cAMP/StAR pathway. In women, LH activates ovarian theca cells to make androgens (aromatized to estrogen by granulosa cells under FSH) and the midcycle LH surge triggers ovulation, follicular rupture, and corpus luteum formation.
Is LH the same as hCG?
No, but they are closely related. hCG is structurally similar to LH and binds the same LH/hCG receptor, but it has a longer plasma half-life. Because of this, hCG is often used clinically as an LH surrogate to trigger ovulation and support the luteal phase, especially in the US where recombinant LH is not broadly approved.
Is recombinant LH approved?
Recombinant human LH (lutropin alfa; Luveris, and Pergoveris with FSH) is approved in the European Union and several other jurisdictions for follicular development in women with profound LH deficiency. It is not broadly approved in the United States.
What are the reported side effects and contraindications of LH?
LH carries a moderate risk profile. Reported contraindications and considerations include active or prior cancer history, thyroid conditions, and pregnancy or nursing. It should only be used under professional medical supervision.
