Human Chorionic Gonadotropin · Pregnyl
Human Chorionic Gonadotropin (HCG) is a naturally occurring glycoprotein hormone (~37 kDa) composed of two subunits (alpha and beta). The alpha subunit is shared with LH, FSH, and TSH; the beta subunit confers biological specificity. HCG mimics luteinizing hormone (LH) by binding to LH/CG receptors on Leydig cells in the testes, stimulating intratesticular testosterone production and preventing testicular atrophy during exogenous testosterone replacement therapy (TRT). It is FDA-approved for hypogonadism and certain fertility indications. HCG is essential in TRT protocols to maintain testicular function, fertility potential, and intratesticular hormonal milieu.
SubQ or IM. Consistent timing. Often every other day or 2-3x per week. Pin alone.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
HCG binds to LH/CG receptors on Leydig cells, activating cAMP/PKA signaling to stimulate steroidogenesis (testosterone, estradiol, progesterone, DHEA synthesis within the testes). This maintains intratesticular testosterone (ITT) concentrations, which are 50-100x higher than serum levels and essential for spermatogenesis. During TRT, exogenous testosterone suppresses pituitary LH secretion via negative feedback, causing Leydig cell inactivity and testicular atrophy. HCG replaces the missing LH signal, keeping Leydig cells active and testes at normal volume. HCG also stimulates aromatase activity in Leydig cells, which means estradiol production increases alongside testosterone.
Days 1-14: Testicular response begins. ITT levels start to recover if previously suppressed.
Weeks 2-8: Testicular volume stabilizes or recovers. Estradiol levels may rise (monitor).
Ongoing: Continuous use alongside TRT. Monitor via labs (total T, free T, estradiol, LH, FSH, semen analysis if fertility relevant).
Each reference below was re-fetched from its PubMed record, and the quoted sentence was confirmed to appear in that abstract and to support the claim it sits under. Follow any of them to read the source.
Evidence boundary from the checked abstract: No patient became azoospermic during concomitant testosterone replacement and human chorionic gonadotropin therapy.
No patient became azoospermic during concomitant testosterone replacement and human chorionic gonadotropin therapy.
Evidence scope. This entry supports only the exact statement quoted from the live abstract; it does not independently verify OnePin's displayed dose, route, frequency, formulation, population, or broader mechanism.
Claims we could not support
No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.
Dose/route: 250-500 IU per injection; SubQ or IM injection; 2-3 times per week. No checked live PubMed abstract verified this exact displayed dose, route, and frequency for the same molecule/formulation and relevant population.
Primary safety claim: No primary safety text present in source JSON. No checked live PubMed abstract directly verified this source-JSON safety claim at the displayed formulation, route, and regimen.
Testicular preservation during TRT
Well-established medical indication. Standard of care recommendation in TRT protocols.
FDA-approved for this purpose. Maintains spermatogenesis during exogenous testosterone use.
The HCG diet is not supported by evidence. FDA has warned against OTC HCG weight loss products. Any weight loss is from the 500-calorie diet, not HCG.
Two different questions: what is documented about running these together, and what is documented about drawing them into the same syringe. A good pharmacological partner can still have to be pinned separately.
Check any specific pair in the Stack & Interaction Checker, which answers both questions separately. Absence of a documented conflict is not evidence of safety.
SubQ
Renal (intact and degraded fragments)
Storage. BAC water reconstitution: 30-60 days refrigerated at 2-8C. Sterile water reconstitution: 24-48 hours only. BAC water is essential for multi-dose vials. Unreconstituted vials stable at room temperature or refrigerated per manufacturer. Protect from light.
FDA-approved for hypogonadism, cryptorchidism, and certain fertility indications. Prescription required. WADA prohibited under S2. Compounded versions available. Schedule III in some contexts.
Put it to work
Open HCG straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
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