Gonadorelin — testicular maintenance while on TRT.

Gonadorelin is a synthetic decapeptide identical to endogenous gonadotropin-releasing hormone (GnRH). It triggers the pituitary to release LH and FSH, which in turn signal the testes to maintain spermatogenesis and intratesticular testosterone production.

On exogenous TRT, the body's LH/FSH signal shuts down via negative feedback — which causes testicular atrophy and suppresses fertility. Gonadorelin (or hCG) bypasses that shutdown by stimulating the system downstream of the brain's feedback loop.

Native GnRH is released from the hypothalamus in pulses every 60–120 minutes. Each pulse triggers a coordinated LH/FSH release from the pituitary. Gonadorelin is the synthetic form of that pulse signal.

On TRT, the brain stops sending GnRH pulses because circulating T is already high. Subcutaneous gonadorelin re-introduces the pulse signal at the pituitary level, restoring LH/FSH output and keeping the testes active. Unlike hCG (which mimics LH directly), gonadorelin acts upstream — preserving the full HPG axis architecture.

Gonadorelin tends to fit:

• TRT patients who want to preserve testicular volume
• Patients planning future fertility (active or theoretical)
• Patients who've come off hCG due to supply issues
• TRT patients with libido/mood complaints that didn't resolve on T alone — the LH signal has independent CNS effects

Patients who have completed family-building and don't care about testicular size are a reasonable opt-out — but most TRT patients we see want it as a baseline part of the protocol.

Typical clinical protocol: 100–200mcg subcutaneous injection, 2–3× per week. Because GnRH's natural half-life is short (~2–10 minutes), gonadorelin is dosed more frequently than hCG but at smaller per-dose amounts.

Pinned to the same days as the testosterone injection in most patients. Lab checks at 8–12 weeks include LH, FSH, and intratesticular markers as needed.

Most patients notice testicular volume preservation within 4–6 weeks of starting. Patients who'd already atrophied on TRT without gonadorelin typically see volume recovery over 8–12 weeks. CNS effects (libido/mood) often reported within 2–4 weeks.

Vektor includes gonadorelin in our standard TRT protocol for patients who want testicular maintenance. Sourced through our U.S. 503A compounding pharmacy in a bacteriostatic-water- reconstitutable vial. We'll switch to hCG when clinically warranted, but gonadorelin is our default — supply has been more stable since the 2022 hCG shortages.