What is Testosterone and Testosterone Therapy?

Testosterone is a hormone made by your body and is responsible for the normal growth and development of the male sex organs and for maintenance of other sexual characteristics. In men, testosterone is produced by the testes, the reproductive glands that also produce sperm. The amount of testosterone produced by testes is regulated by the hypothalamus and the pituitary gland.  For men, testosterone helps maintain:

• Bone density
• Fat distribution
• Muscle strength and mass
• Red blood cell production
• Sex drive
• Sperm production

If you have an unusually low level of testosterone (hypogonadism), your doctor may prescribe a synthetic version of testosterone. You may be able to choose from testosterone injections, patches or gels.  Some testosterone replacement theory effects may include:

• Growth and maturation of prostate, and male sex organs
• Development of male hair distribution such as facial hair
• Changes in body muscle mass and strength and fat distribution
• Sex drive and sexual function
• Mood and energy level
• Bone strength

Normal levels of testosterone

In healthy men, there is a range for testosterone levels (also known as T levels) that is considered normal. The brain and the testes work together to keep testosterone in this range. When levels of testosterone are below normal, the brain signals the testes to make more. When there is enough testosterone, the brain signals the testes to make less. Normal levels of testosterone are based upon age.

What happens to testosterone level with age?

Testosterone peaks during adolescence and early adulthood. As you get older, your testosterone level gradually declines — typically about 1 percent a year after age 30.

Does a naturally declining testosterone level cause the signs and symptoms of aging?

Some men have a lower than normal testosterone level without signs or symptoms. For others, low testosterone may cause:

• Changes in sexual function. This may include reduced sexual desire, fewer spontaneous erections — such as during sleep — and infertility.
• Changes in sleep patterns. Sometimes low testosterone causes insomnia or other sleep disturbances.
• Physical changes. Various physical changes are possible, including increased body fat, reduced muscle bulk and strength, and decreased bone density. Swollen or tender breasts (gynecomastia) and hair loss are possible. You may experience hot flashes and have less energy than you used to.
• Emotional changes. Low testosterone may contribute to a decrease in motivation or self-confidence. You may feel sad or depressed, or have trouble concentrating or remembering things.

It's important to note that some of these signs and symptoms are a normal part of aging. Others can be caused by various underlying factors, including medication side effects, thyroid problems, depression and excessive alcohol use. A blood test is the only way to diagnose a low testosterone level.