Male Hypogonadism Home A-Z Health Information Health Library A-Z Male Hypogonadism Overview Male hypogonadism refers to a condition wherein insufficient amounts of testosterone (hormone responsible for male sexual development and reproductive function) are produced by the testes. It can be congenital or acquired due to injury, infection, or other medical conditions. Symptoms Reduced muscle mass, fatigue, decreased libido, and infertility. Diagnosis Measuring testosterone levels through blood tests and assessing symptoms and medical history. Treatment Testosterone replacement therapy to restore normal levels, which can improve symptoms and overall quality of life. If fertility is a concern, additional treatments like gonadotropin injections may be used to stimulate sperm production.