Testosterone is the sex hormone that helps boys become men. This hormone is key during puberty and the development of male physical features. Testosterone helps to maintain men’s muscle strength and mass, facial and body hair, and a deeper voice. Testosterone levels can affect men’s sex drive, erections, mood, muscle mass and bone density. Testosterone is also needed for men to produce sperm.
Some men have low levels of testosterone. This is called hypogonadism, or low-T.
A man’s testosterone level normally decreases with age. About 4 out of 10 men over the age of 45 have low testosterone. It is seen in about 2 out of 10 men over 60, 3 out of 10 men over 70, and 3 out of 10 men over 80 years old.