What happens to testosterone levels with age?

As men age, a decline in testicular production of testosterone are seen, as well as an increase in sex hormone binding globulin, both of which act to decrease bioavailable testosterone.[3] With this gradual decline, the beneficial effects of testosterone could be diminished and negatively affect physical and emotional well-being.
Male hypogonadism is a condition in which the body does not produce enough of the testosterone hormone; the hormone that plays a key role in masculine growth and development during puberty. Hypogonadism can significantly reduce the quality of life and has resulted in the loss of livelihood and separation of couples, leading to divorce. It is also important for doctors to recognize that testosterone is not just a sex hormone. There is an important research being published to demonstrate that testosterone may have key actions on metabolism, on the vasculature, and on brain function, in addition to its well-known effects on bone and body composition.