Gonadorelin vs HCG on TRT: Preserving Testicular Function

Written by Adam Maggio | Medically reviewed by Dr. Mitchell Ross, MD, ABAARM

Both Gonadorelin (GnRH analogue) and HCG (LH mimic) can preserve testicular function and size during TRT. HCG is more commonly used (500–1000 IU every other day). Gonadorelin (100 mcg twice daily) is an alternative that works upstream via the hypothalamus. Both prevent testicular atrophy and maintain intratesticular testosterone.

Why Testicular Function Matters on TRT

When men begin testosterone replacement therapy, the exogenous testosterone suppresses the hypothalamic-pituitary-gonadal (HPG) axis, leading to reduced LH and FSH secretion. Without LH stimulation, the Leydig cells in the testes stop producing testosterone, and the testes begin to atrophy. This testicular atrophy represents a loss of the testes' ability to produce intratesticular testosterone (which is 50–100 times higher than serum testosterone and essential for spermatogenesis) and other testicular hormones.

HCG: The Standard Approach

Human Chorionic Gonadotropin (HCG) is a glycoprotein hormone that mimics the action of LH, directly stimulating Leydig cells to produce intratesticular testosterone. When used alongside TRT, HCG maintains testicular size, preserves intratesticular testosterone production, and maintains sperm production in most men. HCG is the most commonly used agent for testicular preservation on TRT. Typical dosing: 500–1,000 IU subcutaneously every other day, or 1,500 IU three times per week. HCG also increases estradiol production, which may require AI management in some men.

Gonadorelin: The Upstream Alternative

Gonadorelin is a synthetic version of gonadotropin-releasing hormone (GnRH), the hypothalamic hormone that normally stimulates the pituitary to release LH and FSH. When administered in a pulsatile fashion (mimicking the natural pulsatile release of GnRH), Gonadorelin stimulates the pituitary to produce LH and FSH, which in turn stimulate the testes. The advantage of Gonadorelin over HCG is that it works upstream — it stimulates the entire HPG axis rather than bypassing the pituitary. Typical dosing: 100 mcg subcutaneously twice daily.

Comparing HCG and Gonadorelin

HCG is more extensively studied, widely available, and has a well-established track record for testicular preservation on TRT. Gonadorelin is a newer option that has gained popularity as an alternative to HCG, particularly in the US where HCG availability has been affected by regulatory changes. Both are effective for their primary purpose of maintaining testicular function during TRT.