Human Chorionic Gonadotropin (HCG) 10,000 IU injection is primarily used in the treatment of female infertility by inducing ovulation and supporting pregnancy. It works by mimicking the luteinizing hormone, which triggers the release of the egg from the ovary. In men, it is used to increase sperm count and treat conditions like hypogonadism or delayed puberty. HCG can also be used in boys to help testicular descent in cases of undescended testes. The hormone injection is administered under medical supervision, often in conjunction with other fertility treatments, to improve reproductive outcomes.