The Role of Testosterone in Men
Testosterone is a key male hormone primarily produced in the testicles, although small amounts of testosterone are produced in the adrenal glands, located above the kidneys. This potent hormone is necessary for the development and maintenance of male features.
Testosterone production is regulated by the hypothalamus and pituitary glands in the brain. These glands are, in turn, regulated by the amount of testosterone in the blood stream. Like many hormones, the regulation of testosterone by the body includes a feedback loop.
Men will begin testosterone production in the womb, at approximately seven weeks after conception. The level of testosterone produced by men rises during puberty and reaches a peak in the late part of the teenage years. For a while, testosterone production remains stable, but after the age of 30, testosterone production begins to decrease a little each year.
Production of testosterone by the developing fetus is necessary for development of the male genital organs. If not enough testosterone is produced, a condition known as hypogonadism occurs. In the developing fetus, absence of adequate testosterone can result in the failure of development of the male organs.
During puberty, as testosterone levels rise, the hormone causes growth of the testicles, penis, and public hair. Rising testosterone
levels are also responsible for the growth of body hair and the development of muscle mass. Testosterone causes an increase in production of proteins that are needed to form muscle and it also causes an increase in the release of growth hormone, which results in increased muscle mass. An increased testosterone level at puberty causes the voice to deepen. The hormone is also responsible for sexual desire and production of sperm.
Testosterone and Sexual Activity
Testosterone levels rise during periods of sexual activity or stimulation. During periods of sexual inactivity, testosterone levels may drop. Some men with erectile dysfunction (ED) have low testosterone levels that can be corrected to restore sexual health.
Bone density in men is partially dependent upon a normal testosterone level, and men with low levels of testosterone may develop osteoporosis and bone fractures. Testosterone signals the bone marrow to produce red blood cells. The hormone influences fat metabolism, allowing men to burn fat efficiently. In men with low testosterone levels, body fat may increase.
Testosterone in men influences behaviors like aggression and competitiveness. It helps men maintain a sense of well-being and self-confidence, so in men with low testosterone levels, fatigue and depression can result. Men with low testosterone may have difficulty concentrating or even sleeping.
Testosterone supplementation can help men with low levels of testosterone, but should not be taken by men with normal testosterone levels.