Summary

Gonadorelin is a synthetic decapeptide identical to endogenous gonadotropin-releasing hormone (GnRH), used clinically to diagnose and treat hypothalamic-pituitary-gonadal (HPG) axis disorders. It stimulates LH and FSH release from the pituitary when administered in a pulsatile manner. It is a Prescription-Only Medicine (POM) in the UK.

Mechanism

Gonadorelin binds to the GnRH receptor (GNRHR) on gonadotrope cells of the anterior pituitary, stimulating synthesis and release of LH and FSH. Pulsatile administration (every 60–120 minutes) is stimulatory, while continuous administration downregulates GnRH receptors and suppresses gonadotropin release — the mechanism exploited by GnRH agonists like leuprolide for androgen deprivation therapy. LH stimulates Leydig cells to produce testosterone; FSH stimulates Sertoli cells to support spermatogenesis.

Evidence base

Evidence Grading: Moderate

Human clinical data: Well-established diagnostic and therapeutic use for hypothalamic hypogonadism, including Kallmann syndrome. Pulsatile gonadorelin therapy has been shown to induce puberty and fertility in both sexes. Multiple case series and clinical studies support its use in hypothalamic amenorrhoea.

Limitations: Evidence for use beyond established indications (e.g., as a testosterone-restoration alternative to TRT, or in PCT) is largely anecdotal. No large RCTs compare gonadorelin to standard TRT for general hypogonadism. Pulsatile administration is technically demanding.

Key gap: Controlled trials of gonadorelin for non-classical indications are lacking.

Protocols

Clinical protocols use pulsatile infusion of 5–20 mcg every 90–120 minutes via programmable pump. Diagnostic bolus: 100 mcg IV or SC. In research discussion contexts, 50–100 mcg SC is referenced. Pulsatile delivery is essential for stimulatory effects; continuous infusion will suppress the HPG axis.

Gonadorelin is a Prescription-Only Medicine (POM) in the UK, licensed for diagnostic testing and treatment of hypothalamic hypogonadism. Supply without a prescription violates the Human Medicines Regulations 2012. Research-grade material sold as a research chemical occupies a regulatory grey area, but the MHRA's 2026 guidance on research peptide labelling applies.

Vendor notes

Gonadorelin for clinical use is available by prescription only. Research-grade gonadorelin may be available from some UK research chemical suppliers. Verify COAs and purity. See the vendor vetting guide for evaluation criteria.

References

  1. Schally AV, et al. Isolation and properties of the FSH and LH-releasing hormone. Biochemical and Biophysical Research Communications. 1971;43(2):393-399.
  2. Crowley WF Jr, et al. The physiology of gonadotropin-releasing hormone (GnRH) secretion in men and women. Recent Progress in Hormone Research. 1985;41:473-531.
  3. Buchter D, et al. Pulsatile GnRH or human chorionic gonadotropin/human menopausal gonadotropin as effective treatment for men with hypogonadotropic hypogonadism: a review of 42 cases. European Journal of Endocrinology. 1998;139(3):297-303.
  4. Leyendecker G, et al. Pulsatile administration of GnRH in hypothalamic amenorrhea. Upsala Journal of Medical Sciences. 1984;89(1):19-31.