Androgen deficiency refers to a type of medical condition characterized by low levels of androgenic activity in the human body. It indicates that the level of male sex hormones, specifically testosterone, is lower than the requirement in a healthy adult. There are various signs and symptoms of androgen deficiency, such as exhaustion and lethargy, loss of body hair, diminished sex drive, melancholy, decreased ejaculate production, etc. It can be caused by impairments in testicles, hypothalamus or pituitary gland. The diagnosis of androgen deficiency is done by utilizing a variety of evaluations, such as blood tests, physical examinations, medical histories and other tests. Testosterone replacement therapy TRT is used to treat androgen deficiency. Topical creams, oral medications, transdermal patches and intramuscular injections are examples of TRT procedures. It is a popular treatment for men who have symptomatic hypogonadism. This book unravels the recent studies on testosterone replac