Testosterone is a hormone found in humans, as well as in other animals. In men, the testicles primarily make testosterone, while womens ovaries also make testosterone, though in much smaller amounts. Testosterone is the major sex hormone in males and is essential to the development of male growth and masculine characteristics. Here are some of the things testosterone does for men:

• Regulates sex drive: Testosterone is thought to regulate sex drive (libido) in men.

• Maintains bone mass: Testosterone plays a role in bone density and maintaining bone health. As men age, bone density decreases. A healthy level of testosterone helps protect against bone diseases like osteoporosis.

• Affects muscle mass and strength: Testosterone affects muscle mass and strength in men.

• Contributes to red blood cell production: Testosterone contributes to the production of red blood cells in men.

• Affects mental health: Testosterone affects thinking ability, mood, and memory in men. Men with low levels of testosterone may suffer from depression, fatigue, and general irritability.

• Enhances libido and sense of well-being: Testosterone enhances libido (sex drive) and a sense of well-being in men.

If a man has significantly low levels of active (free) testosterone and symptoms such as generalized weakness, low energy, disabling frailty, or depression, he may be eligible for testosterone therapy.