FSH vs Gonadorelin

Binds FSH receptors on Sertoli cells in testes to support sperm maturation and inhibin B production. In women, binds granulosa cell FSH receptors to drive follicular growth and estradiol production.

FSH (follicle-stimulating hormone) is an endogenous heterodimeric glycoprotein hormone produced and secreted by pituitary gonadotrophs, composed of a non-covalently associated common alpha subunit shared with LH, TSH, and hCG, and a unique FSH-specific beta subunit that confers receptor specificity; it is the primary regulator of gametogenesis in both sexes, acting on ovarian granulosa cells and testicular Sertoli cells to drive reproductive development. FSH activates its cognate receptor (FSHR) through cAMP-mediated signaling to stimulate follicular maturation and estradiol synthesis in the ovary via aromatase upregulation, and to support spermatogenesis in the testis by promoting Sertoli cell function and germ cell proliferation; FSH levels rise dramatically at menopause as negative feedback from ovarian estrogen declines. A Cochrane systematic review and meta-analysis established that recombinant FSH preparations are clinically equivalent to urinary-derived gonadotropins for ovarian stimulation in assisted reproductive technology cycles, providing the evidence base underlying current ART practice; this review supports the use of recombinant FSH as the standard of care for controlled ovarian hyperstimulation. FDA-approved recombinant FSH preparations — follitropin alfa (Gonal-f) and follitropin beta (Follistim) — require a prescription and are indicated for ovulation induction and ART in women and for hypogonadotropic hypogonadism in men; endogenous FSH is not administered as a therapeutic agent, and research-grade recombinant FSH is used as a cell culture tool and reproductive biology research compound.

Synthetic GnRH that binds pituitary GnRH receptors; pulsatile dosing stimulates LH/FSH release; used to maintain HPG axis during TRT

Gonadorelin is the synthetic form of endogenous gonadotropin-releasing hormone (GnRH), the hypothalamic decapeptide that drives the pulsatile reproductive axis by stimulating pituitary release of LH and FSH. When delivered in a pulsatile pattern mimicking the hypothalamic pulse generator, gonadorelin effectively restores normal gonadotropin secretion and reproductive function in individuals with hypothalamic hypogonadism. Peer-reviewed clinical studies demonstrate efficacy of pulsatile gonadorelin pump therapy for testosterone restoration in men with congenital hypogonadotropic hypogonadism, as well as for ovulation induction in women with hypothalamic amenorrhea. Gonadorelin is a prescription peptide requiring specialist oversight; continuous rather than pulsatile administration produces paradoxical gonadotropin suppression, making context of use clinically critical. Gonadorelin dosage in TRT support contexts: in men on testosterone replacement therapy, gonadorelin is commonly used off-label to maintain testicular function and endogenous testosterone production capacity. Subcutaneous doses of 100 mcg administered twice weekly are frequently cited in TRT clinical protocols for this purpose — injected at a pulsatile rather than continuous delivery pattern to preserve LH/FSH signaling. This application requires physician supervision due to the dose-timing sensitivity; the paradoxical suppression from continuous dosing is a clinically important consideration that distinguishes gonadorelin from simpler TRT adjuncts. Gonadorelin vs hCG: both are used in men's health contexts to maintain testicular function alongside testosterone therapy, but they act at different levels of the HPG axis. hCG acts directly at the Leydig cell LH receptor to drive testicular testosterone production, bypassing the pituitary. Gonadorelin acts at the pituitary to stimulate endogenous LH and FSH release — preserving the full hypothalamic-pituitary axis rather than just the downstream testosterone signal. The clinical distinction matters for fertility: gonadorelin preserves FSH stimulation of sperm production alongside testosterone, while hCG stimulates testosterone without independently driving FSH. Telehealth hormone therapy providers offering gonadorelin are listed in the PeptideBase directory.