Human Chorionic Gonadotropin

hCG functions by binding to LH receptors in the Leydig cells of the testes. This mimics the action of natural LH, prompting increased testosterone synthesis. The hormone also stimulates estrogen production, which is important for maintaining muscle fullness and overall hormonal balance during PCT. Users report that this stimulation helps prevent excessive muscle loss and supports recovery.

Pharmacologically, hCG has a relatively short half-life, necessitating frequent administration to maintain stable blood levels. It’s crucial to understand the hormone's action is dependent on functional testes; individuals with pre-existing testicular damage may experience limited benefit.

The primary research application of hCG lies in Post-Cycle Therapy (PCT) following the cessation of anabolic steroid use. Athletes typically run hCG to accelerate the recovery of the hypothalamic–pituitary–gonadal axis, which is suppressed by exogenous testosterone. This helps restore natural testosterone production more quickly.

While less common, some researchers investigate its potential in treating hypogonadism and male infertility. However, these applications are outside the scope of typical bodybuilding-related research. It's also studied as an adjunct to Testosterone Replacement Therapy (TRT) for maintaining spermatogenesis.

Intermediate users typically administer hCG at doses ranging from 500–1000 IU administered every other day, starting approximately two days after the final steroid injection. A common cycle length is 10-20 days, though this varies based on the ester used in the preceding cycle (longer esters require longer PCT). More advanced users may utilize protocols of 2000–4000 IU per week split into multiple injections.

It's important to note that individual responses vary significantly. Bloodwork is essential to monitor testosterone levels and adjust dosage accordingly. Prolonged use or excessive dosages can lead to downregulation of LH receptors, rendering the hormone ineffective.

Users report potential side effects including gynecomastia (due to estrogen conversion), testicular shrinkage (with prolonged use), and increased water retention. Hepatotoxicity is generally not a concern with hCG itself, but it can exacerbate existing liver issues.

A Post-Cycle Therapy (PCT) protocol incorporating aromatase inhibitors (e.g., Anastrozole) and selective estrogen receptor modulators (SERMs) (e.g., Clomid, Nolvadex) is often recommended to manage estrogen levels and mitigate side effects. Age 21+ only. Regular bloodwork is crucial for monitoring hormone levels, liver function, and overall health.

Mechanism of action

Human Chorionic Gonadotropin binds to LH receptors in Leydig cells, stimulating testosterone synthesis and estrogen production; it mimics endogenous luteinizing hormone (LH), supporting gonadal function.