HCG
Also known as: Human Chorionic Gonadotropin, Gonadotrofina Coriônica Humana
Molecular Identifiers
Molecular Formula
C1105H1770N318O336S26
CAS Number
9002-61-3
UNII
20ED16GHEB
Molecular Weight
~36.7 kDa (heterodímero); 25719.77 g/mol (cadeias polipeptídicas, sem glicosilação)
Overview
Human chorionic gonadotropin that mimics LH. Maintains testicular function during TRT. Research in fertility preservation.
FDA-approved as Pregnyl (intramuscular injection) and Ovidrel (recombinant choriogonadotropin alfa) for female infertility treatment, ovulation induction and spermatogenesis stimulation in men.
The main clinical interest around HCG is its mimicry of endogenous LH: by stimulating Leydig cells, it preserves intratesticular testosterone production and spermatogenesis. For this reason it is widely prescribed as an adjuvant to testosterone replacement therapy (TRT) to prevent testicular atrophy and maintain fertility, as well as in ovulation induction protocols in reproductive medicine.
HCG is a prescription medication dispensed at standard pharmacies as Pregnyl (Organon/Merck) and approved by the FDA also as Ovidrel (recombinant choriogonadotropin alfa). Its use in male endocrinology as a "bridge" during TRT is established off-label practice. WADA lists it as a substance prohibited for male athletes.
Within the HPG axis, hCG is the outlier of the group: it does not act on the pituitary like gonadorelin, triptorelin, and cetrorelix, nor on the hypothalamus like kisspeptin-10 — it acts directly on testicular Leydig cells, mimicking LH and bypassing pituitary levels. This is why it preserves steroidogenesis even when the axis is suppressed (e.g., TRT), whereas GnRH agonists/antagonists depend on a responsive pituitary. It is also a large glycoprotein, in contrast with the others, which are short peptides.
Large glycoprotein (237 amino acids, ~36.7 kDa) — hormone composed of alpha and beta subunits
Half-life
~24-36 hours
Administration Route
Subcutaneous or intramuscular
Category
Hormonal Regulation
Mechanism of Action
- LH (luteinizing hormone) mimicry
- Leydig cell stimulation
- Maintenance of intratesticular testosterone production
- Spermatogenesis support
Dosage Protocol
Data compiled from the literature. This does not constitute medical advice.
| Parameter | Value |
|---|---|
| Dose | 250-500 IU per injection |
| Frequency | 2-3 times per week |
| Timing | Any time of day |
| Duration | As per protocol |
Reported Side Effects
Adverse effects described in the literature. Severity and frequency vary between individuals.
- Gynecomastia
- Fluid retention
- Headache
- Irritability
- Injection site pain
Product Properties
| Purity | >97% |
| Appearance | White lyophilized powder |
| Solubility | Soluble in water and bacteriostatic water |
| Source | Recombinant DNA technology or extraction from pregnant women urine |
| Storage | Lyophilized: -20°C for up to 2 years, 2-8°C for up to 6 months. Reconstituted: 2-8°C for up to 30 days. Protect from light and moisture. Avoid repeated freeze-thaw cycles. |
Presentations & Preparation
Vials of HCG found in the research market:
Reconstitution
- Diluent: Bacteriostatic water
- Volume: According to vial concentration
- Slowly inject the diluent against the vial wall
- Gently swirl until fully dissolved
- Never shake
Storage
- Lyophilized: Refrigerated 2-8°C
- Reconstituted: Refrigerated 2-8°C (up to 30 days)
- Protect from direct light
- Do not freeze after reconstitution
Scientific Studies
Published studies on HCG.
Human chorionic gonadotropin monotherapy for the treatment of hypogonadal symptoms in men with total testosterone > 300 ng/dL
Madhusoodanan V, Patel P, Lima TFN, Gondokusumo J, Lo E, Thirumavalavan N, Lipshultz LI, Ramasamy R
Concomitant intramuscular human chorionic gonadotropin preserves spermatogenesis in men undergoing testosterone replacement therapy
Hsieh TC, Pastuszak AW, Hwang K, Lipshultz LI
Related Peptides
Argipressin
5-20 IU or 1-4 mcg/kg · As clinically needed
Cetrorelix
0.25-3 mg per injection · Once daily (0.25 mg) or single dose (3 mg)
Gonadorelin
100-200 mcg per injection · 2-3 times per week
Kisspeptin-10
1-10 mcg per injection · Per research protocol
α-MSH
0.5-2 mg per injection · Once daily or every other day
Oxytocin
10-40 IU intranasal or 50-200 mcg subcutaneous · 1-2 times daily