FSH vs Triptorelin

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.

Potent GnRH agonist; single pulse stimulates LH/FSH surge and restores HPG axis after suppression (e.g., post-steroid cycle)

Triptorelin is a synthetic decapeptide GnRH agonist with a longer half-life than endogenous GnRH, used clinically to produce controlled hormonal suppression of the reproductive axis via receptor downregulation. Unlike the brief stimulatory effect of native GnRH, continuous or depot administration of triptorelin paradoxically desensitizes pituitary GnRH receptors, producing sustained suppression of LH, FSH, and sex hormone levels through a process known as medical castration. Clinical trials have established triptorelin efficacy for androgen deprivation therapy in prostate cancer, treatment of central precocious puberty, and hormonal management of endometriosis and uterine fibroids. Triptorelin is an FDA-approved prescription medication (Trelstar) available in depot formulations; it requires specialist-supervised monitoring due to an initial hormonal flare on commencement and the significant physiological effects of prolonged sex hormone suppression. Triptorelin for HPTA restart (PCT context) Outside its approved indications, triptorelin has been discussed in post-cycle therapy (PCT) and testosterone replacement therapy (TRT) restart contexts. The rationale is mechanistic: a single low dose of triptorelin triggers a brief, intense LH and FSH pulse before inducing pituitary downregulation — this initial agonist surge may be sufficient to re-sensitise a suppressed hypothalamic-pituitary-gonadal (HPG) axis following prolonged androgen administration that has blunted endogenous LH/FSH production. Some research and anecdotal literature describes single-dose triptorelin protocols (typically 100–200mcg administered once) as an HPTA restart approach, with the goal of re-initiating endogenous testosterone production. This use is not FDA-approved, not evaluated in randomised controlled trials for this indication, and not a standard of care in any guideline. It represents an off-label research and community-practice area. Triptorelin's mechanism — producing sustained hormonal suppression — means that incorrect dosing or repeated administration would achieve the opposite of the desired restart effect; this context requires qualified clinical supervision. PeptideBase does not endorse off-label use; this is informational context about how the compound is discussed in research and clinical community settings.