A synthetic GnRH used for fertility preservation during TRT and as a diagnostic tool for pituitary function.
Gonadorelin is a synthetic decapeptide identical to endogenous gonadotropin-releasing hormone (GnRH). It was FDA-approved as Factrel for diagnostic evaluation of pituitary gonadotroph function. In modern clinical practice, it has found significant off-label use as an HCG alternative during testosterone replacement therapy (TRT) to maintain testicular function, fertility, and intratesticular testosterone production.
When administered in pulsatile fashion (mimicking natural hypothalamic GnRH release), gonadorelin stimulates LH and FSH production from the pituitary. This maintains the HPG axis signal that exogenous testosterone suppresses, preserving testicular volume and spermatogenesis during TRT — critical for men who wish to maintain fertility.
The shift from HCG to gonadorelin accelerated after the FDA classified HCG as a biologic (rather than a drug) in 2020, making it more expensive and less accessible through compounding pharmacies. Gonadorelin emerged as the primary alternative for HPG axis maintenance during TRT.
Clinical experience demonstrates gonadorelin effectively maintains LH, FSH, and intratesticular testosterone during TRT when dosed appropriately (typically 100-200 mcg subcutaneously 2x daily or 3x weekly). Testicular volume preservation and maintained spermatogenesis have been documented in clinical practice.
Diagnostic use (the FDA-approved indication) involves a single IV or SC dose followed by serial LH/FSH measurements to assess pituitary reserve. The pulsatile dosing for TRT support is off-label but widely practiced in men's health clinics.
📚 Key Reference: PMID: 6337482 (gonadorelin clinical use)
Generally well-tolerated. Injection site reactions are most common. Multiple daily injections can be burdensome. Overstimulation of the pituitary is possible (headache, flushing). Continuous (non-pulsatile) administration can paradoxically suppress LH/FSH — proper dosing protocol is critical. Consult your provider.
FDA-approved as Factrel for diagnostic use. Off-label use for TRT support is common. Available through compounding pharmacies.