HCG (Human Chorionic Gonadotropin)

What is HCG (Human Chorionic Gonadotropin)?

Human Chorionic Gonadotropin is a common hormonal substance that can be used to mimic and amplify the effects of two main endogenous gonadotropins, the luteinizing hormone (LH) and the Follicle stimulating hormone (FSH). The Human chorionic gonadotropin (HCG) is a chemical glycoprotein that is comprised of 237 amino acids. HCG has the exact structural properties and chemical characteristics and functions as the luteinizing hormones (LH). Because of these similarities, many physicians prescribe HCG whenever a patient is in need of the physiological effects of the luteinizing hormones. The LH and the HCG have the ability to bind to a common receptor, HCG has a higher affinity for the receptors than the LH. They share the same characteristics and the exact mode of binding but after the bonds, the processes that take place are different in each of the two hormones. Lots of people use HCG as medicine to lose weight and have had great results.

The main reasons why HCG is preferred over the Luteinizing hormone is because; it is more stable in nature so it forms more stable bonds. It has a greater affinity for the receptors compared to the Luitenizing Hormones so it bonds easier and quicker, it has higher and greater rates of physiological processes and activities with a longer lifespan than the Luteinising hormone. The HCG can live to perform its activities for hours while the LH has a half-life that exists only for minutes. The short half-life of the luteinizing hormone is, however, essential for its functions since it facilitates short and periodic variations of its exposure to the body system. The HCG’s longer half-life span and its higher affinity for receptors including its binding abilities are some of the factors that enable it to be more biologically active than the Luteinizing hormones.


                       HCG Structure

The HCG and the LH are regarded as analogous hormones because of their similarity in structure, chemical composition, and functioning. They have identical alpha units which produce similar biological activities when linked to appropriate beta sub-units. Additionally, the HCG alpha subunit is similar to that of the follicle stimulating hormone, the Luteinizing hormone and the thyroid stimulating hormone. The HCG’s beta sub-unit is amazingly unique to its own forms.

The Background And The History Of HCG

The Human Chorionic Gonadotropin (HCG) and its recombinant formulation which is known as the choriogonadotropin alfa (r-HCG) is a polypeptide that acts as a gonadal stimulating hormone. It is naturally secreted by the placenta during pregnancy. The non-recumbent hormonal products can be manually harvested from the urine of a pregnant woman. To manufacture a recumbent HCG, you have to recombine the HCG products using various DNA techniques in the Chinese-Hamster-Ovary cells, (CHO). The modes of action of the HCG and the r-HCG are similar in nature and match exactly with the functional characteristics of the Luteinising hormones (LH). The HCG is commonly used as a substitute for the Luteinising hormone in a case of low and inadequate secretion of the hormone.

HCG is used to treat hypogonadotropic hypogonadism/cryptorchidism in males. It was first introduced as an effective treatment for this condition back in the 1930’s and it served as the only available hormonal agent that could treat this condition until the early 1970’s when the gonadotropin releasing hormone was developed. The gonadotropin releasing hormone is analogous to the HCG so it can effectively play the same role as HCG. Nevertheless, HCG is still used to treat hypogonadotropic hypogonadism in males and most of the time, it is used in conjunction with heliotropin and menotropins.

Urine-based HCG that is harvested from the urine of pregnant women was approved by the FDA in 1939. It then received consequent approvals for other indicators in 1973. Ovidrel, which was the first recombinant HCG (r-HCG) received its FDA approval on September 20th in the year 2000. It received an approval for female fertility with the main function of inducing the final stage of maturation of the follicles. Ovidrel pre-filled syringes received their FDA approval on October 2003 while the Ovidrel vials have ceased from being manufactured.

HCG on Testosterone Replacement Therapy

The Human gonadotropic hormones regulates the fertility levels in males by binding to the receptors that are found in the male reproductive tissues. HCG is normally administered in conjunction with the testosterone replacement therapy. When exogenous testosterone is administered to a patient, it affects the male reproductive tissues by creating effects and changes on the balance of the hypothalamus pituitary-gonadal axis, (HPG-axis). Because of the various effects of the androgens and the influence caused by the aromatization of testosterone into oestrogen, a negative feedback is initiated, so the secretion and the production of endogenous testosterone is greatly reduced.

The negative feedback mechanism from the oestrogen and androgens also reduces the secretion of the gonadotropic releasing hormones (GnRH), which in turn reduces the general secretion of gonadotropins. Gonadotropins are responsible for the general functions of the gonads i.e. Hormone production and facilitating physiological activities around the male gonads. In simpler terms, the reduction in the production of the Follicle Stimulating Hormones (FSH) and the Luteinising Hormones (LH) subsequently reduce the production of testosterone and limits the process of spermatogenesis in the testes. Testicular atrophy is experienced as a result of insufficient signaling of gonadotropins.  HCG medication is therefore used during and after testosterone replacement therapy so that it can restore and maintain the size of the testicles, facilitate spermatogenesis and the continuous production of testosterone from the testes.

When HCG is administered, it performs similar activities to the Luteinising hormone so it acts as a supplemental gonadotropin. HCG also stimulates the Leydig cells to synthesise intratesticular testosterone which is essential for the spermatogenesis that occurs in the Sertoli cells of the testes.

HCG is used during testosterone replacement therapy to maintain the levels of the intratesticular testosterone and normal spermatogenesis, to effectively achieve this, 500 IUs of HCG should be administered daily during the testosterone replacement therapy.

The Role Of HCG In Hypogonadotropic Hypogonadism

In patients with hypogonadotropic hypogonadism from the ages of 12 to 24 years, HCG of 1500 to 2000 IUs was administered 3 times in a week for 8 weeks to them intramuscularly. The results obtained indicated an increase in the testosterone levels, an increase in penile length and an increase in the volume of the testicles.

The Role Of HCG In The Hypothalamus pituitary-gonad axis in males. (HPG-axis).

The main tissues that are involved in various functions in the HPG-axis are;

 The pituitary glands. These glands produce the two gonadotropins i.e. the follicle stimulating hormone (FSH), and the luteinizing hormone (LH).

The Hypothalamus. This takes part in the production of the gonadotropin-releasing hormones (GnRH).

The Testes. The male testes contain the Sertoli cells and the Leydig cells. The hormone testosterone is produced in the male testes then it metabolises into an array of metabolites which include oestrogen and progesterone. These metabolites facilitate spermatogenesis.

The Hormones That Are Involved In The HPG-axis include;

The Luteinizing hormone

Its main function is to bind with the receptors on the Leydig cells and the interstitial cells of the testes. They promote the secretion of androgens by the Leydig cells.

The Gonadotropin-releasing hormone

This hormone signals the pituitary glands to release the luteinizing hormones and the follicle stimulating hormones in periodic and varying quantities.

The follicle stimulating hormones

This hormone binds to the Sertoli cells in the testes and facilitates a favorable environment for spermatogenesis. They also regulate the maturity rates of the sperms.


Androgens have a very strong suppressive effect on the synthesis of gonadotropins by the pituitary glands. They have receptors on the hypothalamus that direct a negative feedback mechanism to the secretion of gonadotropic releasing hormones.


Oestrogens have their receptors in the hypothalamus which dictate a negative feedback to the secretion of gonadotropic releasing hormones. it negatively regulates the levels of the gonadal cells in an autocrine manner.


Progesterone inhibits the secretion of gonadotropic hormones.


The Human-chorionic-gonadotropin can mimic the functional properties of the luteinizing hormone and the follicle-stimulating-hormones, so it is used as a substitute for the two gonadotropic hormones.

The Mechanism Of Action Of HCG

The mode of action of HCG generally depends on the purpose for which it is being administered and its expected use and outcomes. It also depends on the sex of the patient and the levels of maturity of the patient receiving the medication.

The following is a brief description of HCG’s mode of action in the different levels.

In Adults and adolescent males

In adults and adolescents with a condition of hypogonadotropic hypogonadism, HCG mimics the characteristics of the Luteinizing hormones therefore, it stimulates the production of testosterone by the Leydig cells and it facilitates the process of spermatogenesis in the testes’ seminiferous tubules. HCG also stimulates the production of androgens which causes the development of secondary sexual characteristics in men. These include; the widening of the shoulders, the deepening of the voice, growing of facial and pubic hair and a muscular frame formation. The Human chorionic gonadotropin (HCG) also stimulates the Leydig cells to produce oestrogen which can produce gynecomastia if it rises to sufficient levels in the body system. Once the HCG treatment is initiated, it takes an average of 70 to 80 days for the cells to reach the spermatozoal stage. A positive response to the treatment is indicated by the development of masculine features, the standardisation of testosterone levels in your body, the activation of testicular growth and the increased volumes of sperms due to their constant production. HCG can help to restore fertility in men who are suffering from hypogonadotropic hypogonadism if correctly administered for many months or years. This treatment can be combined with menotropins and urofollitropin medications for even better results.

In Adult Females

In a number of selected females with fertility problems, The HCG acted similarly to the luteinizing hormones. It also appears to have similar but minimal characteristics as the follicle stimulating hormones in women. By stimulating the HCG together with or after the administration of follitropin, menotropins and clomiphene, the normal surge that is produced by the luteinizing hormones after ovulation can be mimicked. The HCG facilitates and promotes the development and maintenance of the corpus lutetium and it also oversees the production of progesterone. After this medication, the final luteinization/maturation of the oocytes is completed so ovulation can be induced using various timed insemination techniques. Another process can be the retrieval of the oocytes for an assisted reproductive technology. e.g. an In Vitro fertilization, (IVF). after a successful pregnancy, HCG is naturally secreted by a woman’s placenta to support and facilitate the continued secretion of female hormones and maintenance of the corpus lutetium.

In Male Infants and Children

In male infants, the normal descending of the testicles is completed by 3 months of age. The testicular descent occurs because of an endogenous testosterone production that is stimulated by pituitary gonadotropins i.e. LH and FSH. This is a response to the lack of exposure to the maternal oestrogen after birth. The testosterone surges reach their peak within 60 days after birth. In children and male infants with Cryptorchidism, HCG functions as a Luteinizing hormone and causes the Leydig cells to produce testosterone in bits that can induce the descent of the testes. Hormonal stimulation by the HCG can result to an early pseudopuberty and in rare cases, the responses to the hormonal therapy can be temporary. Various hormonal therapies like the administration of HCG have not replaced any surgical treatments for the condition which is orchiopexy within the first 2 years of life.  Some studies on animals have shown that HCG can be used as a solution to orchiopexy to help preserve fertility but so far, no human data is available.

The activity of HCG on the general body composition in all sexes and ages. HCG has no known effects on an individual’s appetite or on the mobilisation and distribution of fat. It can not be used as a treatment for obesity. But in sports, some athletes use it as an undetectable anabolic steroid. HCG can increase the body’s production of testosterone and epitestosterone substantially without altering the ratio of these hormones in the urine past abnormal levels. Complex urine testing systems are being developed which will enable the discriminate testing of the HCG medication and doping in sports. In case you require more information on this medication feel contact us today and we will give you the best way forward. FDA Statement on HCG “HCG has not been demonstrated to be an effective adjunctive therapy in the treatment of obesity. There is no substantial evidence that it increases weight loss beyond that resulting from caloric restriction, that it causes a more attractive or ‘normal’ distribution of fat, or that it decreases the hunger and discomfort associated with calorie-restricted diets.”

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