Kisspeptin

Kisspeptin is a neuropeptide produced in the hypothalamus and the master regulator of the hypothalamic-pituitary-gonadal (HPG) axis — the hormonal cascade responsible for testosterone, estrogen, LH, and FSH production. Without kisspeptin signaling, the reproductive hormone system essentially goes offline.

Testosterone production follows a chain of command: Hypothalamus → Pituitary → Testes. Kisspeptin neurons fire the first signal in this chain, triggering GnRH release, which tells the pituitary to release LH, which tells the testes to make testosterone. Kisspeptin works at the top of the chain, supporting natural testosterone production rather than replacing it.

In research settings, kisspeptin is typically administered intravenously or subcutaneously in pulsatile fashion to mimic the body's natural pattern. Clinical protocols for compounded use most commonly involve subcutaneous injection. The native kisspeptin-10 and kisspeptin-54 forms are both used clinically; longer analogues with extended half-lives are in development.

Kisspeptin addresses the root cause for men with secondary hypogonadism (the problem is upstream), but will have limited effect in men with primary testicular failure. Lab testing is essential to determine whether a patient is a good candidate, and your physician will determine the appropriate form and dosing schedule.