Gonadorelin (Factrel, Lutrepulse)
Gonadorelin (Gonadotropin-Releasing Hormone, GnRH, LHRH)
Synthetic decapeptide identical to native hypothalamic GnRH; previously FDA-approved as a diagnostic agent (Factrel, NDA018123) and for pulsatile therapy of hypothalamic amenorrhea (Lutrepulse, NDA019687); supported by a systematic review of 103 studies (5,328 patients) for spermatogenesis induction; now used off-label in TRT protocols for fertility preservation (PMID 38128110).
Last updated: 2026-03-10
Safety Summary
Gonadorelin is generally very well tolerated, consistent with it being structurally identical to an endogenous hormone. In the systematic review of gonadotropin therapy for HH (PMID 38128110), the pooled proportion of patients experiencing gynecomastia with GnRH therapy was 4% (95% CI 0%-10%), acne was 5% (95% CI 0%-37%), and injection site reactions were 42% (95% CI 9%-78%). The injection site reaction rate was elevated by pulsatile pump delivery. The main safety concern is that repeated daily dosing at 200-400mcg can cause GnRH receptor desensitization and paradoxical suppression of LH/FSH within 10-14 days. Single or intermittent dosing does not carry this risk.
Known Side Effects
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Who Should NOT Use This
GnRH stimulation can alter hormonal balance critical for pregnancy maintenance. Factrel and Lutrepulse labels listed pregnancy as a contraindication.
Acute stimulation of LH/FSH and downstream sex hormones could potentially fuel hormone-dependent tumors. GnRH agonists carry this warning for the initial surge period; native GnRH carries a similar acute risk.
Standard drug hypersensitivity contraindication.
Pituitary receptor desensitization and HPG-axis suppression occur with repetitive high-dose exposure, opposing the intended physiologic pulsatile action.
Gonadotrophin-releasing hormone appears on the WADA Prohibited List under class S2.
Talk to Your Doctor
Before considering Gonadorelin (Factrel, Lutrepulse), discuss it with your healthcare provider. Ask about potential interactions with your current medications, whether it is appropriate for your health conditions, and what monitoring may be needed.
Sources: [1-10]
Evidence Assessment
Tier 1: Gonadorelin was FDA-approved for two indications -- as a diagnostic agent (Factrel, NDA018123, approved 1974) for pituitary function testing, and as a therapeutic agent (Lutrepulse Kit, NDA019687, approved 1989, orphan drug) for pulsatile treatment of hypothalamic amenorrhea. Both approvals were supported by clinical trial data meeting FDA standards. A systematic review of 103 studies encompassing 5,328 patients provides Level I evidence for efficacy in inducing puberty and spermatogenesis in hypogonadotropic hypogonadism (PMID 38128110). The pharmacology is among the most well-characterized of any peptide, supported by Nobel Prize-winning research. Both FDA-approved products are now discontinued for commercial (not safety) reasons, but the evidence base that supported approval remains intact. The primary contemporary off-label use in TRT fertility preservation has a weaker direct evidence base (clinical practice data, mechanistic rationale, small studies), but the overall evidence profile for the peptide warrants Tier 1.
1Gonadotropins for pubertal induction in males with hypogonadotropic hypogonadism: systematic review and meta-analysisPMID 38128110
First author et al. - European Journal of Endocrinology (2024) - systematic review and meta-analysis - 103 studies, 5,328 patients from 21 countries
GnRH was used in 28.2% of studies (29 studies). Pulsatile GnRH achieved pooled spermatogenesis rate of 76% (95% CI 65%-86%). Gonadotropins induced significant increases in testicular volume, penile size, and testosterone in >98% of analyses. Median treatment duration 18 months. Gynecomastia rate with GnRH: 4% (95% CI 0%-10%). Injection site reactions with GnRH: 42% (95% CI 9%-78%). High study heterogeneity (I2=69% for GnRH spermatogenesis).
Limitations: High heterogeneity across studies in treatment dose, duration, and patient populations. Majority observational studies. Publication bias likely. Only English-language studies included. Not all 103 studies were direct gonadorelin-only trials.
2Is the triptorelin stimulation test comparable to the gonadorelin stimulation test in diagnosing central precocious puberty in boys?PMID 41207293
Seo JH, Yoo M, Lee K, Choi J, Choe Y, Yang S - Annals of Pediatric Endocrinology & Metabolism (2025) - matched retrospective cohort - 55 boys (23 gonadorelin, 32 triptorelin; 17 matched per group)
Gonadorelin stimulation test peak LH was 9.70 mIU/mL vs 19.55 mIU/mL for triptorelin (P=0.041). Gonadorelin peak occurred at 45 minutes (12/17 patients) vs >=90 minutes for triptorelin. The triptorelin test may overdiagnose CPP due to higher peak LH values. Gonadorelin remains the reference standard for the GnRH stimulation test.
Limitations: Small sample size (17 per group after matching). Retrospective design. Tests not performed on same individuals. Single-center study.
3Diagnostic accuracy of the triptorelin stimulation test for central precocious puberty in girlsPMID 41384863
Chioma L, Bizzarri C, Longobardi M, Mainieri F, Porzio O, D'Agostini M, Paone L, Bottaro G - Endocrine Connections (2025) - retrospective diagnostic cohort - 341 girls (239 gonadorelin, 102 triptorelin; 143 CPP, 198 NPT)
Gonadorelin protocol used 100mcg IV with sampling at 30, 60, and 90 minutes. ROC analysis identified gonadorelin LH cut-off of 4.70 IU/L (sensitivity 100%, specificity 87%, AUC 0.982). Triptorelin showed comparable diagnostic accuracy (LH cut-off 7.14 IU/L, AUC 0.985). Native GnRH noted as expensive and commercially limited in many countries.
Limitations: Retrospective, non-parallel comparison. Not all subjects underwent both tests. Single center.
4Micropump infusion of gonadorelin in the treatment of hypogonadotropic hypogonadism in patients with pituitary stalk interruption syndrome: cases analysis and literature reviewPMID 25131486
Shao WM, Bai WJ, Chen YM, Liu L, Wang YJ - Journal of Peking University (Health Sciences) (2014) - case series - 2
Two patients with hypogonadotropic hypogonadism caused by pituitary stalk interruption syndrome improved androgen-deficiency symptoms and had higher gonadotropin levels after 12 weeks of pulsatile gonadorelin micropump therapy.
Limitations: Only two cases with short follow-up and no control group.
5The Pulsatile Gonadorelin Pump Induces Earlier Spermatogenesis Than Cyclical Gonadotropin Therapy in Congenital Hypogonadotropic Hypogonadism MenPMID 30567896
Zhang L, Cai K, Wang Y, Ji W, Cheng Z, Chen G, Liao Z - American Journal of Men's Health (2019) - comparative cohort study - Not specified in available abstract
Pulsatile gonadorelin pump therapy achieved spermatogenesis at median 6 months vs 14 months for cyclical hCG+hMG therapy. Spermatogenesis occurred in 90% of pulsatile GnRH group vs 83.3% of hCG+hMG group (difference not statistically significant). Both therapies produced significant increases in testis volume and penile length.
Limitations: Non-randomized comparative study. Full paper not present in filtered corpus -- accessed via secondary source.
6Pulsatile GnRH Is Superior to HCG in Therapeutic Efficacy in Adolescent Boys With Hypogonadotropic HypogonadismPMID 25978110
Gong C et al. - Journal of Clinical Endocrinology & Metabolism (2015) - comparative study - Referenced in systematic review (PMID 38128110)
Pulsatile GnRH was superior to HCG alone in therapeutic efficacy for adolescent boys with hypogonadotropic hypogonadism. Better testicular growth and spermatogenesis outcomes.
Limitations: Details from systematic review citation; full paper data limited in available sources.
7Factrel (gonadorelin hydrochloride) - FDA NDA018123
Wyeth/Hikma - FDA Drugs@FDA (1974) - FDA approval (NDA) - Clinical trial data supporting NDA approval
FDA-approved gonadorelin as diagnostic agent for evaluating functional capacity and response of gonadotrophs of the anterior pituitary. Administered as single 100mcg IV dose. Active ingredients: Gonadorelin Hydrochloride at 0.1mg, 0.2mg, and 0.5mg strengths. Product now discontinued.
Limitations: Approval data from 1974. Product now discontinued. Full clinical trial data not available in current source files.
8Lutrepulse Kit (gonadorelin acetate) - FDA NDA019687 (Orphan Drug)
Ferring Laboratories - FDA Drugs@FDA (1989) - FDA approval (NDA, orphan drug) - Clinical trial data supporting NDA approval
FDA-approved for pulsatile intravenous administration to induce ovulation in women with hypothalamic amenorrhea due to absent or inadequate endogenous GnRH secretion. Orphan drug designation. Active ingredient: Gonadorelin Acetate at 0.8mg and 3.2mg strengths. Product now discontinued.
Limitations: Product discontinued. Full clinical trial data not available in current source files.
9Use of pulsatile gonadotropin-releasing hormone (GnRH) in patients with functional hypothalamic amenorrhea (FHA) results in monofollicular ovulation and high cumulative live birth rates: a 25-year cohort
Quaas P, Quaas AM, Fischer M, De Geyter C - Journal of Assisted Reproduction and Genetics (2022) - retrospective cohort (25-year) - 66 women, 212 ovulation induction attempts
Pulsatile GnRH (10mcg every 90 minutes) achieved 96% ovulation rate, 80.5% pregnancy rate per treatment, and 65.9% live birth rate per treatment in women with functional hypothalamic amenorrhea. 75% monofollicular ovulation, reducing multiple pregnancy risk.
Limitations: Retrospective design. Single-center. Referenced via secondary source (EXA-222b4c0bbcc8); full text not in papers directory.
10The Response to Gonadotropin-Releasing Hormone and hCG in Men with Prior Chronic Androgen Steroid Abuse and Clinical Hypogonadism
Flanagan JN, Lehtihet M - Hormone and Metabolic Research (2015) - clinical study - 26 men (13 prior AAS use, 5 hypogonadal, 8 controls)
A single 100mcg dose of gonadorelin raised LH levels in all groups. LH levels more than doubled in all treated groups. 35% of AAS users (5/13) reached LH levels within the bottom 5% of the reference range after just one injection, suggesting partial HPG axis recovery potential.
Limitations: Small sample size. Referenced via secondary source (EXA-222b4c0bbcc8). Single-dose assessment, acute hormonal surrogate endpoint only.