Late-onset hypogonadism.

Late-onset hypogonadism is a clinical and biological syndrome associated with advancing age and characterized by typical symptoms and a deficiency in serum testosterone levels. It is a common condition but often underdiagnosed and undertreated. The main symptoms of hypogonadism are reduced libido/erectile dysfunction, reduced muscle mass and strength, increased adiposity, osteoporosis/low bone mass, depressed mood, and fatigue. Testosterone replacement therapy is only warranted in the presence of both clinical symptoms suggesting hormone deficiency and decreased hormone levels. It improves libido and sexual function, bone density, muscle mass, body composition, mood, erythropoiesis, cognition, quality of life, and cardiovascular disease.