Human Chorionic Gonadotropin (HCG) is a glycoprotein hormone produced naturally during pregnancy by trophoblast cells. In the performance and hormone optimization context, HCG is used primarily for two purposes: (1) maintaining testicular function and fertility during testosterone replacement therapy (TRT) or anabolic steroid cycles, and (2) as part of post-cycle therapy (PCT) to restart natural testosterone production. HCG mimics Luteinizing Hormone (LH) and directly stimulates the Leydig cells of the testes to produce testosterone and maintain testicular volume. It is an essential tool for men on TRT who wish to preserve fertility.
Notes
HCG is FDA-approved for treating hypogonadism and as a fertility treatment. It is widely used off-label alongside TRT to maintain testicular function and fertility. The FDA has restricted compounding pharmacies from producing HCG as of 2020, making pharmaceutical brands the primary source.
HCG is structurally similar to Luteinizing Hormone (LH) and binds to the LH/CG receptor on Leydig cells in the testes. This activates the cAMP signaling cascade, stimulating steroidogenesis: the conversion of cholesterol to pregnenolone and ultimately to testosterone. By directly stimulating the Leydig cells, HCG maintains intratesticular testosterone (ITT) levels, which are essential for spermatogenesis. During TRT or AAS use, exogenous testosterone suppresses LH and FSH via negative feedback on the hypothalamus and pituitary. Without LH stimulation, the Leydig cells atrophy and testosterone production ceases. HCG prevents this atrophy by providing LH-like stimulation even when endogenous LH is suppressed.
HCG is a large glycoprotein (approximately 36 kDa) that must be injected. After subcutaneous injection, absorption is gradual with peak levels at 6-12 hours. The half-life is approximately 24-36 hours. HCG is metabolized primarily by the kidneys. Its LH-mimicking activity persists for the duration of its plasma presence. Importantly, HCG does not stimulate FSH receptors; for full spermatogenesis recovery, FSH (or a SERM to stimulate endogenous FSH) may also be needed.
Typical Dose
On-cycle (TRT/AAS support): 250-500 IU every other day, or 500-1000 IU twice per week. PCT use: 1000-2000 IU every other day for 2-3 weeks (higher doses for PCT). Fertility preservation during TRT: 500 IU three times per week is a common and effective protocol.
Frequency
Two to three times per week for on-cycle use. Every other day for PCT protocols. Consistent scheduling is important.
Administration
Subcutaneous or intramuscular injection. Subcutaneous (abdominal fat) is the most common and convenient method. Intramuscular injection is also effective but less commonly used for the small volumes involved.
Half-Life
24-36 hours (terminal half-life of intact HCG)
Contraindications
**HCG itself does not require PCT, but it is commonly PART of a PCT protocol.** When using HCG as part of PCT: 1. Run HCG for 2-3 weeks to restart testicular function 2. Then switch to a SERM (Nolvadex 20-40 mg/day or Clomid 25-50 mg/day) for 4-6 weeks to restart pituitary LH/FSH production 3. Do NOT run HCG and SERMs simultaneously for extended periods, as HCG suppresses LH through negative feedback, counteracting the SERM's purpose When using HCG on-cycle with TRT: no PCT for HCG specifically; it is a supportive tool.