HCG (Human Chorionic Gonadotropin)

Overview

Human chorionic gonadotropin is a hormone produced during pregnancy that, in men, acts on the same receptor as luteinising hormone. That property makes it the standard tool for a specific problem: when external androgens suppress the body's own hormonal axis, the testes stop receiving the signal to produce testosterone — and shrink.

HCG replaces that signal. It does not restore the axis, but it keeps the organ at its end functional.

Mechanism of Action

The hormonal axis works in a chain: the hypothalamus releases GnRH, which prompts the pituitary to release LH and FSH, which in turn signals the testes to produce testosterone. External androgens interrupt this chain at the top — the body registers sufficient testosterone and shuts down its own signal.

HCG intervenes at the bottom of the chain. It is structurally similar enough to LH to activate the same receptor on the Leydig cells in the testes. The testes therefore continue to produce testosterone even though no signal is arriving from above. Volume and responsiveness are preserved.

Two consequences follow from this that are regularly overlooked. First, testicular testosterone production also generates estradiol locally — HCG raises estrogen levels directly, independently of what is aromatizing elsewhere. Second, HCG itself acts suppressively on the release of the body's own LH, which is precisely why it does not belong in the recovery phase.

Continuous high dosing carries a further problem: the Leydig cells become less responsive to constant stimulation. The effect diminishes with exactly the dosing intended to maximise it.

Typical Context

Two applications are common. During a cycle, low doses of 250 to 500 IU twice a week are used to preserve testicular volume and responsiveness. This is not cosmetic — testes that have been inactive for months recover more slowly than those that kept working.

The second application is the run-up to the recovery phase. HCG is given for two to three weeks at higher doses and then stopped before the actual post-cycle plan begins. The logic is sequential: first restore the testes' capacity to respond, then restart the higher-level axis. Running both at once is counterproductive, since HCG itself suppresses LH release.

In medicine, HCG is used in fertility treatment and as an addition to ongoing testosterone replacement therapy, where preserving fertility matters.

Side Effects & Risks

• Rising estradiol through direct stimulation of testicular estrogen production
• Water retention, gynecomastia risk as a consequence of the elevated estradiol
• Desensitisation of the Leydig cells at continuous high doses
• Distortion of LH measurements in blood work
• Acne, mood changes
• Local reactions at the injection site
• Rarely: headache, fatigue

Blood Work & Monitoring

• Estradiol (sensitive) — rises under HCG, often more than expected
• Total/free testosterone — to check the response
• LH and FSH — not informative during HCG use; measure only after an adequate interval
• Hematocrit & hemoglobin

Harm-Reduction Notes

• Keep the dose low during a cycle; 250 to 500 IU twice a week preserves function without driving estradiol
• Do not use during the recovery phase — HCG suppresses the body's own LH release and works against the goal
• Do not interpret LH values measured during use; the test cannot distinguish HCG from LH
• Watch estradiol; estrogenic symptoms under HCG often stem from testicular production rather than from the cycle compounds
• Preserved testicular volume is not the same as a recovered axis
• Reconstituted HCG must be refrigerated and has a limited shelf life
• Sterile single-use needles, rotate injection sites