HCG (Human Chorionic Gonadotropin)

HCG (Human Chorionic Gonadotropin) (Inj)

Human chorionic gonadotropin (hCG) is a placental glycoprotein hormone with LH-receptor activity. In research and clinical contexts it is used to stimulate testicular Leydig cells to increase intratesticular testosterone and support spermatogenesis via luteinizing hormone/chorionic gonadotropin receptor (LHCGR) agonism.

Dosing Protocols

Reconstitute: Add 2.0 mL bacteriostatic water → 2,500 IU/mL concentration.
Typical dosing: 500 IU subcutaneous, 3× weekly (Mon/Wed/Fri) for testicular maintenance during TRT.
Easy measuring: At 2,500 IU/mL, 1 unit = 25 IU on a U-100 insulin syringe.
Storage: Lyophilized: refrigerate at 2–8 °C; reconstituted: refrigerate at 2–8 °C for up to 60 days.

Schedule: Subcutaneous injections 3 times weekly for 8–16 weeks.
Cycle Length: 8–12 weeks typical; extend to 16+ weeks for severe suppression cases.
Goal: Maintain testicular function and fertility during testosterone replacement therapy or restore endogenous testosterone production post-cycle.

Frequency: Inject 3 times weekly subcutaneously (e.g., Monday/Wednesday/Friday). This yields a total weekly dose of 1,500 IU.

Phase	Dose	Syringe (U-100)
TRT Maintenance	500 IU	20 units (0.20 mL) × 3/week
PCT Loading (Weeks 1–4)	1,500 IU	60 units (0.60 mL)
PCT (Weeks 5–8)	2,000 IU	80 units (0.80 mL)
PCT Taper (Weeks 9–12)	1,000 IU	40 units (0.40 mL)

Benefits

• Stimulates Leydig-cell testosterone production via LHCGR agonism
• Supports intratesticular testosterone (ITT), a key driver of spermatogenesis
• Used in male infertility protocols to induce/augment spermatogenesis
• Can help maintain testicular function during exogenous androgen exposure (context-dependent)
• In females, triggers final follicular maturation/ovulation in fertility settings
• Useful probe for HPG-axis function in endocrine research

Mechanism of Action

• Binds LHCGR on Leydig cells and ovarian theca/granulosa cells
• Activates Gs→adenylyl cyclase→cAMP→PKA signaling
• Upregulates steroidogenic acute regulatory protein (StAR) and steroidogenic enzymes to increase steroidogenesis
• In ovaries, mimics LH surge to promote oocyte maturation and luteinization

Side Effects

• Headache, irritability, mood changes
• Water retention/edema
• Gynecomastia or nipple tenderness (via increased estradiol)
• Acne/oily skin
• Testicular discomfort
• Injection-site pain/redness
• In women: ovarian hyperstimulation syndrome (OHSS) risk

Side Effect Management

• Monitor testosterone and estradiol; adjust dose/frequency to reduce estrogenic side effects
• Avoid large bolus dosing when possible; split dosing reduces peaks
• Track blood pressure and fluid retention
• Rotate injection sites and use sterile technique
• In fertility settings, ultrasound/lab monitoring is standard

Contraindications

• Known hypersensitivity to hCG preparations
• Hormone-sensitive malignancies (e.g., prostate/breast) unless specifically indicated
• In women: high OHSS risk or ovarian cysts not due to PCOS
• Uncontrolled endocrine disorders should be stabilized first
• Pregnancy (outside fertility-treatment context)

Research Citations

1. Induction of spermatogenesis with gonadotropins in hypogonadotropic hypogonadism. Hum Reprod Update. PubMed | DOI
2. Clinical use of human chorionic gonadotropin in male hypogonadism and infertility. Fertil Steril. PubMed | DOI
3. Ovarian hyperstimulation syndrome. N Engl J Med. PubMed | DOI
4. Human chorionic gonadotropin and LH receptor signaling in steroidogenesis. Endocr Rev. PubMed | DOI

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