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Research information only. Not medical advice. 18+ only. Not FDA-approved for human therapeutic use.

Gonadorelin

Also known as: GnRH, LH-RH, LHRH, Gonadotropin-Releasing Hormone, Luteinizing Hormone-Releasing Hormone, Factrel

Hypothalamic decapeptide hormone / GnRH agonist (native sequence)

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What it is

Gonadorelin is a synthetic decapeptide identical to endogenous gonadotropin-releasing hormone (GnRH), synthesized and released by the hypothalamus. It regulates production and release of the gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by the adenohypophysis. When administered parenterally, native GnRH was initially used diagnostically as a test of adenohypophyseal reserve of LH and FSH, and subsequently used therapeutically to treat hypothalamic hypogonadal and infertility states. In male athletes, misuse of gonadorelin triggers testosterone increase. In tambaqui fish, gonadorelin at 60 µg/kg body weight decreased fshβ expression and increased circulating E2, 17α-hydroxyprogesterone, and testosterone; the authors propose that downregulation of fshβ may promote final oocyte maturation and ovulation by favoring a hormonal environment with increased progesterone influence.

Class: Hypothalamic decapeptide hormone / GnRH agonist (native sequence)

What it's studied for

  • Diagnostic stimulation test (LH/FSH reserve; central precocious puberty; amenorrhea) Human observational
    • GnRH stimulation testing in 865 girls with idiopathic central precocious puberty (ICPP) showed that higher BMI is associated with lower LH response; BMI should be considered when interpreting GnRH-stimulation tests. PMID 25645648 Fu et al., Obesity (Silver Spring) 2015
    • Simplified gonadorelin stimulation test in 292 girls showed LH/FSH ratio >0.9 at 15 min after gonadorelin had diagnostic sensitivity of 80.1% and specificity of 90.8% for differentiating central precocious puberty (CPP) from premature thelarche (PT); blood sample at 60 min was deemed unnecessary. PMID 15476332 Jiang et al., Zhejiang da xue xue bao 2004
    • Intravenous 80 µg gonadorelin in women with normal menstrual cycle and secondary amenorrhea provoked typical gonadotropin release with LH peak at 30–60 min; relative ascent after second i.v. dose at 120-min interval was not significantly higher than after first dose. PMID 3103350 Vesper et al., Zentralblatt fur Gynakologie 1986
    • Review describes diagnostic and therapeutic uses of GnRH including testing of gonadotropin reserve, treatment of hypogonadism, cryptorchidism, precocious puberty, endometriosis, and hormone-dependent cancers. PMID 2862854 Hammond & Ory, Archives of Internal Medicine 1985
  • Treatment of hypogonadotropic hypogonadism (HH) / induction of spermatogenesis Human observational
    • In 28 azoospermic congenital HH males, pulsatile gonadorelin pump (PGP) induced spermatogenesis significantly earlier (median 6 months) than cyclical gonadotropin therapy (median 14 months; p=0.01); spermatogenesis occurred in 90% of PGP group vs. 83.3% of CGT group (not significant). PMID 30569789 Zhang et al., American Journal of Men's Health 2019
    • Two cases of hypogonadotropic hypogonadism caused by pituitary stalk interruption syndrome treated by pulse infusion of gonadorelin via micropump; androgen deficiency improved and gonadotropin levels promoted at 12 weeks. PMID 25131486 Shao et al., Beijing da xue xue bao 2014
    • Review notes that native GnRH was used therapeutically to treat hypothalamic hypogonadal and infertility states in both men and women. PMID 1835275 Pace et al., American Family Physician 1991
  • Cryptorchidism treatment (intranasal gonadorelin) Mixed
    • In 94 outpatients (mean age 4.16 years) with mono- or bilateral cryptorchidism, intranasal gonadorelin analogues administered for 4 weeks; authors conclude gonadorelin has a role in treating cryptorchidism and should be the first-choice treatment. PMID 2572057 Beretta & Zanollo, Archivio italiano di urologia 1989
    • Double-blind drug evaluation of intranasal gonadorelin spray for undescended testis in infants and children. PMID 2897635 de Muinck Keizer-Schrama et al., Nederlands tijdschrift voor geneeskunde 1988
    • Prospective RCT in 36 unilateral cryptorchid infants (21 GnRH, 15 control): intranasal gonadorelin treatment did not significantly affect penile size, testicular volume, or hormonal levels (LH, FSH, testosterone, Inhibin B, AMH) at time of orchidopexy compared to controls; mid-term treatment considered safe. PMID 35691791 Fiala et al., Journal of Pediatric Urology 2022
  • Neoadjuvant treatment to support spermatogonia maturation before orchidopexy Human RCT
    • Prospective RCT: intranasal gonadorelin in infants with unilateral undescended testis did not show significant effect on penile size, testicular volume, or hormonal levels compared to controls; treatment considered safe in mid-term. PMID 35691791 Fiala et al., Journal of Pediatric Urology 2022
  • Ovulation induction / timed artificial insemination in dairy cattle Animal studies only
    • In 3,938 Holstein cows, gonadorelin hydrochloride (100 µg) vs. gonadorelin diacetate tetrahydrate (100 µg) showed no significant difference in pregnancies per AI (35.7% vs. 38.4%). Other factors (service number, month, SCC, milk protein) affected P/AI. PMID 25979657 Poock et al., Theriogenology 2015
    • In 6,621 lactating dairy cows, 200 µg gonadorelin hydrochloride at G1 of breeding Ovsynch increased P/AI (51.8% vs. 48.6%), ovulatory response (83.0% vs. 70.8%), and peak LH compared to 100 µg; greatest benefit in multiparous cows. PMID 41698585 Lima et al., Journal of Dairy Science 2026
    • In 2,111 services in 1,438 lactating Holstein cows, 200 µg GnRH increased ovulatory response (48.0% vs. 36.1%) vs. 100 µg at Resynch-25 initiation, but did not improve overall fertility. A second GnRH dose 56 h later tended to decrease P/AI. PMID 39603499 Leão et al., Journal of Dairy Science 2025
  • Induction of ovulation / strip spawning in aquaculture fish (tambaqui) Animal studies only
    • Gonadorelin at 60 µg/kg body weight in mature female tambaqui decreased fshβ expression, increased E2, 17α-OHP, and testosterone; 6 of 9 treated females ovulated vs. 0 controls. PMID 40645558 Oliveira et al., Comparative Biochemistry and Physiology Part B 2025
  • Radiolabeled imaging agent (67Ga-cDTPA-gonadorelin) for breast anomaly detection Animal studies only
    • Biodistribution of 67Ga-cDTPA-GnRH in rats; estimated absorbed dose from 185-MBq injection in humans was 5.26 mGy whole body; highest dose in lungs (2.73 mSv). High breast uptake suggests potential for early imaging of breast anomalies and GnRH receptor-positive malignant lesions. PMID 21068688 Shanehsazzadeh et al., Nuclear Medicine Communications 2011
  • Anti-doping detection (analytical methods development) In vitro only
    • Review of bioanalytical approaches (chromatography, immunochemistry, affinity sensing) for gonadorelin detection in doping context; gonadorelin described as a neuropeptide misused in sports competitions. PMID 36858006 Torrini et al., Journal of Pharmaceutical and Biomedical Analysis 2023
    • BELISA assay using polynorepinephrine-based MIP for gonadorelin quantification achieved detection limit of 277 pmol/L with CV% 4.07% in standard solutions and 5.24% in urine; validated by mass spectrometry. PMID 35028691 Torrini et al., Analytical and Bioanalytical Chemistry 2022

Community-reported dosing

RouteDoseFrequency / DurationPopulation / contextSource tier
Intravenous80 µg (intravenous, administered twice at 120-min interval)Single diagnostic session (two-step test)humanResearch PMID 3103350
IntranasalNot specified in abstract (intranasal gonadorelin, administered from age 6 months)From 6 months of age until orchidopexy (mean 11 months of age)humanResearch PMID 35691791
IntranasalNot specified in abstract (LHRH analogue gonadorelin, intranasal)4 weekshumanResearch PMID 2572057
Not specified in abstract (Ovsynch protocol injection)100 µg (2 mL) of either gonadorelin hydrochloride or gonadorelin diacetate tetrahydrateSingle injection at each GnRH step of Ovsynch protocolanimalResearch PMID 25979657
Not specified in abstract (Ovsynch protocol injection)100 µg (2 mL) or 200 µg (4 mL) gonadorelin hydrochloride (Factrel; Zoetis)Single injection at G1 of breeding Ovsynch in Double-Ovsynch protocolanimalResearch PMID 41698585
Not specified in abstract100 µg or 200 µg GnRH (once on d 25, or on d 25 and 56 h later on d 27)Single or two injections within Resynch-25 protocolanimalResearch PMID 39603499
Not specified in abstract60 µg/kg body weightSingle treatment sessionanimalResearch PMID 40645558
Intravenous185 MBq (estimated human injection for dosimetry projection, based on rat biodistribution data)Single intravenous administration (rat study)animalResearch PMID 21068688
subcutaneous injection100 mcgtwice weeklymen on testosterone replacement therapy (TRT) seeking to maintain testicular function and endogenous LH/FSH signaling[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcgdailymen on TRT who prefer daily microdosing for more stable LH/FSH pulsatility[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection250 mcgtwice weeklymen on TRT who feel 100 mcg is insufficient for testicular response[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection500 mcgtwice weeklymen post-anabolic steroid cycle or post-TRT attempting to restore HPTA function[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcgthree times weeklymen on TRT seeking a middle ground between daily and twice-weekly dosing schedules[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection25 mcgdailymen on TRT seeking a very low-dose, highly physiological pulsatile GnRH approach[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcgtwice weeklymen with hypogonadotropic hypogonadism or post-TRT users attempting to restore fertility[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection500 mcgonce weeklypost-cycle or post-TRT men doing HPTA restart[S] Claude Sonnet 4.6 — synthesized from aggregate training data

Tier key: Research = PMID-cited study · [C] = scraped community source · [S] = model-synthesized from aggregate community reports (softer evidence). How we source.

Safety signals

  • Severe anaphylaxis (loss of consciousness, tonic seizures) following intravenous gonadorelin acetate administration in an 8-year-old girl with central precocious puberty; treated with epinephrine, diphenhydramine, and fluids with recovery within 30 min. PMID 26197466
  • IgE-mediated hypersensitivity (wheal-and-flare skin reactions at injection sites) during long-term gonadorelin hydrochloride (Factrel) infusion pump use in a woman with severe hypogonadotropic hypogonadism; treatment was discontinued. PMID 2643043
  • Skin allergic erythema scleroma reported as a common side effect of pulsatile gonadorelin pump in congenital hypogonadotropic hypogonadism men. PMID 30569789
  • Serious bone loss/osteoporosis associated with long-term treatment with long-acting gonadorelin agonist triptorelin in a man with paraphilia. PMID 17971105
  • Serious bone loss/osteoporosis associated with long-term treatment with long-acting gonadorelin agonist triptorelin (reported in Dutch-language case report, same case as PMID 17971105). PMID 17290340
  • Gonadorelin analogs combined with anti-androgens for prostate cancer bone metastasis associated with potential induction of osteoporosis (case report). PMID 2532342

Contraindications

  • History of severe hypersensitivity or anaphylaxis to gonadorelin or its analogues; anaphylaxis has been reported after intravenous gonadorelin acetate, requiring immediate availability of resuscitation equipment. PMID 26197466
  • Prior IgE-mediated hypersensitivity reaction to gonadorelin hydrochloride (Factrel) during infusion pump therapy; treatment was discontinued in a reported case. PMID 2643043

Frequently asked

What is gonadorelin and how does it work?

Gonadorelin is a synthetic decapeptide identical to endogenous gonadotropin-releasing hormone (GnRH), which is synthesized and released by the hypothalamus. It regulates production and release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by the pituitary gland. When administered parenterally, it was initially used diagnostically to test pituitary reserve of LH and FSH, and subsequently used therapeutically to treat hypothalamic hypogonadal and infertility states.

Why is gonadorelin banned by WADA?

Gonadorelin has been listed as a banned substance in sports by the World Anti-Doping Agency (WADA) because misuse by male athletes can trigger a testosterone increase (PMID 35028691; PMID 36858006). Analytical methods including biomimetic immunoassays and mass spectrometry are used in anti-doping controls to detect it in urine samples.

What dose of gonadorelin should I use?

I'm not a medical professional and can't recommend a protocol for you specifically. What research has shown: In diagnostic human studies, 80 µg was administered intravenously in a two-step test. In pulsatile pump therapy for hypogonadotropic hypogonadism, doses and delivery parameters varied by protocol (PMID 30569789; PMID 25131486). In cattle studies, doses of 100 µg and 200 µg have been compared (PMID 41698585; PMID 39603499). No dosing data for self-administration is available in the reviewed literature.

Can gonadorelin be used to treat cryptorchidism in children?

Intranasal gonadorelin has been studied for cryptorchidism treatment. In 94 outpatient boys (mean age 4.16 years), intranasal gonadorelin administered for 4 weeks was reported to have a role in treating cryptorchidism. However, a prospective RCT in 36 infants with unilateral undescended testis found no significant effect on penile size, testicular volume, or hormonal levels at time of orchidopexy compared to controls; mid-term safety was considered acceptable. Please consult a licensed healthcare provider for guidance specific to any individual case.

Is gonadorelin safe? What are the side effects?

Reported safety signals from the literature include: (1) Severe anaphylaxis (loss of consciousness, tonic seizures) following intravenous gonadorelin acetate — administration should be in a setting equipped to handle systemic reactions; (2) IgE-mediated hypersensitivity (wheal-and-flare skin reactions) during long-term infusion pump use; (3) Skin allergic erythema scleroma with pulsatile pump therapy in HH men; (4) Serious bone loss/osteoporosis with long-term use of the GnRH analogue triptorelin (PMID 17971105; PMID 17290340). A prospective RCT in cryptorchid infants found no significant adverse hormonal or developmental effects at mid-term.

How is gonadorelin used to treat hypogonadotropic hypogonadism?

In published studies, pulsatile gonadorelin pump (PGP) therapy and pulse infusion via micropump have been used for hypogonadotropic hypogonadism (HH). In 10 congenital HH men, PGP induced spermatogenesis at a median of 6 months, significantly earlier than cyclical gonadotropin therapy (median 14 months; PMID 30569789). In 2 patients with HH due to pituitary stalk interruption syndrome, pulse infusion via micropump over 12 weeks improved androgen deficiency symptoms and gonadotropin levels. Please consult a licensed healthcare provider for individual management.

Can I stack gonadorelin with testosterone or other compounds?

I can't recommend combining compounds — that's a prescribing decision. Here's what has been studied individually: Gonadorelin (native GnRH) has been studied for hypogonadotropic hypogonadism and spermatogenesis induction (PMID 30569789; PMID 25131486). Its misuse alongside other performance-enhancing agents has not been assessed in the reviewed literature.

Where can I buy gonadorelin?

I don't recommend vendors or sources. Please consult a licensed provider.

Can gonadorelin be taken orally?

The reviewed abstracts do not contain data on oral administration of gonadorelin. One editorial referenced an orally active GnRH antagonist (not gonadorelin itself) as a novel development. Native GnRH (gonadorelin) is described in the reviewed literature as administered parenterally or intranasally (PMID 1835275; PMID 35691791; PMID 2572057). I don't have reliable study data on oral gonadorelin bioavailability. I won't guess — please consult a licensed provider or peer-reviewed literature directly.

Does BMI affect the gonadorelin stimulation test?

Yes, based on a retrospective cohort study of 865 girls with idiopathic central precocious puberty (ICPP): higher BMI was associated with a lower LH response to GnRH stimulation testing. Median peak LH was 9.1 mIU/mL in normal-weight girls vs. 6.2 mIU/mL in obese girls. The authors recommend that BMI should be considered when interpreting GnRH-stimulation test results.

References

  1. [1] PMID 25645648 — GnRH stimulation testing in 865 girls with idiopathic central precocious puberty (ICPP) showed that higher BMI is associated with lower LH response; BMI should
  2. [2] PMID 15476332 — Simplified gonadorelin stimulation test in 292 girls showed LH/FSH ratio >0.9 at 15 min after gonadorelin had diagnostic sensitivity of 80.1% and specificity of
  3. [3] PMID 3103350 — Intravenous 80 µg gonadorelin in women with normal menstrual cycle and secondary amenorrhea provoked typical gonadotropin release with LH peak at 30–60 min; rel
  4. [4] PMID 2862854 — Review describes diagnostic and therapeutic uses of GnRH including testing of gonadotropin reserve, treatment of hypogonadism, cryptorchidism, precocious pubert
  5. [5] PMID 30569789 — In 28 azoospermic congenital HH males, pulsatile gonadorelin pump (PGP) induced spermatogenesis significantly earlier (median 6 months) than cyclical gonadotrop
  6. [6] PMID 25131486 — Two cases of hypogonadotropic hypogonadism caused by pituitary stalk interruption syndrome treated by pulse infusion of gonadorelin via micropump; androgen defi
  7. [7] PMID 1835275 — Review notes that native GnRH was used therapeutically to treat hypothalamic hypogonadal and infertility states in both men and women.
  8. [8] PMID 2572057 — In 94 outpatients (mean age 4.16 years) with mono- or bilateral cryptorchidism, intranasal gonadorelin analogues administered for 4 weeks; authors conclude gona
  9. [9] PMID 2897635 — Double-blind drug evaluation of intranasal gonadorelin spray for undescended testis in infants and children.
  10. [10] PMID 35691791 — Prospective RCT in 36 unilateral cryptorchid infants (21 GnRH, 15 control): intranasal gonadorelin treatment did not significantly affect penile size, testicula
  11. [11] PMID 25979657 — In 3,938 Holstein cows, gonadorelin hydrochloride (100 µg) vs. gonadorelin diacetate tetrahydrate (100 µg) showed no significant difference in pregnancies per A
  12. [12] PMID 41698585 — In 6,621 lactating dairy cows, 200 µg gonadorelin hydrochloride at G1 of breeding Ovsynch increased P/AI (51.8% vs. 48.6%), ovulatory response (83.0% vs. 70.8%)
  13. [13] PMID 39603499 — In 2,111 services in 1,438 lactating Holstein cows, 200 µg GnRH increased ovulatory response (48.0% vs. 36.1%) vs. 100 µg at Resynch-25 initiation, but did not
  14. [14] PMID 40645558 — Gonadorelin at 60 µg/kg body weight in mature female tambaqui decreased fshβ expression, increased E2, 17α-OHP, and testosterone; 6 of 9 treated females ovulate
  15. [15] PMID 21068688 — Biodistribution of 67Ga-cDTPA-GnRH in rats; estimated absorbed dose from 185-MBq injection in humans was 5.26 mGy whole body; highest dose in lungs (2.73 mSv).
  16. [16] PMID 36858006 — Review of bioanalytical approaches (chromatography, immunochemistry, affinity sensing) for gonadorelin detection in doping context; gonadorelin described as a n
  17. [17] PMID 35028691 — BELISA assay using polynorepinephrine-based MIP for gonadorelin quantification achieved detection limit of 277 pmol/L with CV% 4.07% in standard solutions and 5
  18. [18] PMID 26197466 — Severe anaphylaxis (loss of consciousness, tonic seizures) following intravenous gonadorelin acetate administration in an 8-year-old girl with central precociou
  19. [19] PMID 2643043 — IgE-mediated hypersensitivity (wheal-and-flare skin reactions at injection sites) during long-term gonadorelin hydrochloride (Factrel) infusion pump use in a wo
  20. [20] PMID 17971105 — Serious bone loss/osteoporosis associated with long-term treatment with long-acting gonadorelin agonist triptorelin in a man with paraphilia.
  21. [21] PMID 17290340 — Serious bone loss/osteoporosis associated with long-term treatment with long-acting gonadorelin agonist triptorelin (reported in Dutch-language case report, sam
  22. [22] PMID 2532342 — Gonadorelin analogs combined with anti-androgens for prostate cancer bone metastasis associated with potential induction of osteoporosis (case report).
  23. [23] PMID 6 — in-prose reference
  24. [24] PMID 43603499 — in-prose reference
  25. [25] PMID 43 — in-prose reference
  26. [26] PMID 16089294 — in-prose reference
  27. [27] PMID 30611410 — in-prose reference
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