HCG

Understanding HCG: A Patient Guide

Human chorionic gonadotropin—commonly called HCG—is a hormone produced by the body during pregnancy. This hormone consists of two connected parts that work together. One part resembles other reproductive hormones your body makes naturally, while the other part is unique to HCG. When HCG attaches to receptors on your reproductive cells, it starts a series of chemical messages that tell your body to produce reproductive hormones.

Doctors and researchers have discovered that HCG helps bring eggs to maturity and trigger their release, increases progesterone production during early pregnancy, and stimulates testosterone production in men. Because HCG stays active in your body longer than a similar natural hormone, scientists use it to better understand how reproductive systems work and respond to hormone signals.

How Your Body Uses HCG

During pregnancy, special pregnancy-supporting tissue creates HCG. This hormone's job is to keep the corpus luteum—the part of your ovary that produces progesterone—working properly. HCG accomplishes this by attaching to special receptors on reproductive cells and triggering internal chemical signals. For women trying to conceive, HCG helps eggs mature and form the structure that produces progesterone. For men, HCG encourages testosterone production and supports sperm formation when their body isn't making enough hormones naturally.

In some unusual situations, when HCG levels get very high, the hormone can mildly affect thyroid function. Because pregnancy and certain cancers produce large amounts of HCG, doctors can measure this hormone to detect pregnancy or diagnose specific health conditions.

HCG's Physical Makeup

Here's what HCG looks like from a scientific perspective:

Total size: approximately 36.7 kilodaltons (a measure of molecular weight)

Two parts: a smaller part weighing 10,205 units and a larger part weighing 15,547 units

Common names: Human chorionic gonadotropin; Choriogonadotropin; hCG

Identification code (CAS): 9002-61-3

HCG and Women's Reproductive Health

In fertility treatment programs, HCG works like your body's natural reproductive hormone to help eggs complete their development and get released. When doctors give HCG at precisely the right moment, it causes the egg to be released and transforms the egg-producing structure into a progesterone-producing one. This process mirrors what happens naturally when your body releases an egg and mimics your natural hormone surge. Fertility specialists use HCG to control when ovulation happens and to support the early pregnancy phase.

HCG and Men's Reproductive Health

HCG stimulates testosterone-producing cells in the male reproductive system when it connects with specific receptors. Medical studies show that HCG can restore testosterone levels in the testicles and support normal sperm production in men whose bodies aren't producing enough natural reproductive hormones. For this reason, HCG helps treat fertility problems in men and addresses hormone deficiency.

Examining HCG and Weight Loss Claims

Some older weight-loss programs combined HCG with strict dieting. However, careful scientific studies consistently show that HCG doesn't help people lose more weight or change where the body stores fat compared to dieting alone. Every time scientists examine people who lost weight using HCG, they discover that the weight loss comes entirely from eating fewer calories—not from any direct effect of HCG itself.

HCG and Broader Health Effects

When HCG levels climb higher than normal, the hormone can slightly stimulate your thyroid because it's chemically similar to other hormones that affect the thyroid. Very high HCG levels have been associated with temporary thyroid overactivity in certain pregnancy situations. Some cancers also produce HCG abnormally, which helps doctors identify these conditions. Because HCG lasts longer in your bloodstream than similar natural hormones, it maintains longer activity in your body—a feature that makes it valuable for research and medical investigations.

Research Information

Dr. Peter Humaidan, M.D., Ph.D. brought together, edited, and organized the scientific information in this guide. Dr. Humaidan is recognized worldwide as an expert in reproductive medicine who pioneered important advances in triggering ovulation, supporting the early pregnancy phase, and improving fertility treatment methods. His work on HCG and related hormones has influenced how fertility specialists treat patients today.

Dr. Humaidan has written numerous scientific articles about HCG's roles in fertility, triggering egg release, and supporting early pregnancy, helping improve fertility treatment techniques. He has collaborated with accomplished researchers including B. Alsbjerg, A.D. Coviello, W.J. Bremner, B.J. Schoenfeld, and R. Ramasamy on studies examining how reproductive hormones work in both women and men.

This recognition is meant to acknowledge Dr. Humaidan's scientific contributions and those of his collaborators. It should not be understood as approval or endorsement of any commercial company or product. Montreal Peptides Canada has no business relationship with Dr. Humaidan or the researchers mentioned.

Referenced Scientific Literature

1. Humaidan P, Alsbjerg B. GnRHa trigger for final oocyte maturation: is HCG trigger history? Reprod Biomed Online. 2014;29(3):274-280 rbmojournal.com.
2. Coviello AD, Matsumoto AM, Bremner WJ, et al. Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab. 2005;90(5):2595-2602 pubmed.ncbi.nlm.nih.gov.
3. Fink J, Schoenfeld BJ, Hackney AC, et al. Human chorionic gonadotropin treatment: a viable option for management of secondary hypogonadism and male infertility. Expert Rev Endocrinol Metab. 2021;16(1):1-8 pubmed.ncbi.nlm.nih.gov.
4. Lee JA, Ramasamy R. Indications for the use of human chorionic gonadotropic hormone for the management of infertility in hypogonadal men. Transl Androl Urol. 2018;7(Suppl 3):S348-S352 imcwc.com.
5. Habous M, Giona S, Tealab A, et al. Clomiphene citrate and human chorionic gonadotropin are both effective in restoring testosterone in hypogonadism: a short-course randomized study. BJU Int. 2018;122(5):889-897 tau.amegroups.org.
6. Liu PY, Wishart SM, Handelsman DJ. A double-blind, placebo-controlled trial of recombinant human chorionic gonadotropin in older men with partial age-related androgen deficiency. J Clin Endocrinol Metab. 2002;87(7):3125-3135 tau.amegroups.org.
7. ClinicalTrials.gov. Efficacy and Safety of Long Term Use of hCG or hCG Plus hMG in Males With Isolated Hypogonadotropic Hypogonadism (IHH). (Tongji Hospital study NCT03687606) centerwatch.com.