Human Chorionic Gonadotropin or HCG is one of the first hormones produced during pregnancy. Indeed, most home early pregnancy tests work to detect the presence of HCG, and if none is detected, no pregnancy is assumed. HCG is produced in the human body in the placenta and helps to prepare a woman's body for pregnancy. The familiar "morning sickness" or bouts of nausea experienced by many women shortly after they become pregnant is caused by elevated levels of HCG being produced in their bodies. But pharmaceutical forms of HCG have a few other uses. HCG itself is a glycoprotein hormone that contains alpha and beta subunits. The significance of that is that the alpha subunit of the HCG structure is virtually identical to that of the luteinizing hormone (LH), a hormone classified as a gonadotropin that is released by the pituitary gland in the brain. LH is also involved in the pregnancy process, but in a man's body, it promotes the synthesis of testosterone in the Leydig cells of the testes. In some older men, the release of LH fails to properly promote testosterone synthesis and when that happens, low testosterone levels can result. Depending on the degree of symptoms experienced by men with low testosterone levels, testosterone replacement therapy may be in order.
But HCG itself because of its resemblance to LH can significantly boost testosterone levels and that has several implications. Some men who are experiencing early signs of low testosterone production may not want to start testosterone replacement therapy or TRT. The usual reason for this reluctance is that using exogenous forms of testosterone (T) will act as a feedback loop to the pituitary gland, and LH will not be released, What that means is that no testosterone will be produced in the body once a man begins TRT. That can be a problem for a man who wants to have a child because along with no testosterone, the testes will stop producing enough sperm to initiate a pregnancy. In short, the man becomes infertile. HCG is an option for men who may want to produce children and not have to worry about infertility brought on by full TRT. But the HCG can in many cases raise lower T levels sufficient enough to relieve symptoms of low T. This type of testosterone treatment with HCG is usually short-lived and doesn't work after a while.
Another use for HCG injections, and it must be injected because it would be degraded in the gut if consumed orally, is to maintain testicular mass while on TRT. One frequent side effect of TRT is a shrinkage of the testicles. This is caused by a lack of stimulation from LH on the testicles. But since HCG is nearly identical to LH it can maintain both the size of the testicles as well as maintain sperm production for possible future pregnancy purposes (women, not men). HCG . . .