The body produces testosterone naturally, but natural testosterone cannot be used as a medicine. In the normal body, testosterone is released continuously into the bloodstream by the pituitary gland. In males, it is also released by the testes. It reaches different parts of the body, has its effects, and then body enzymes quickly break it down.
When males reach the end of puberty, the amount of testosterone rises suddenly and stays at a high level for four to six months before returning to normal. During this time, the growth plates in the long bones of the arms and legs close, the voice deepens, facial hair begins to grow and the male sex organs grow in size. It is this surge in testosterone that completes the sexual maturation of males.
Some males do not experience this burst of testosterone. When the role of testosterone was discovered, medical researchers tried to treat delayed puberty by giving them testosterone. They discovered that a single dose of testosterone, even a very large one, is so rapidly broken down by body enzymes that it cannot imitate the natural hormone surge. To use natural testosterone for this purpose, a boy would have to have an intravenous infusion bag constantly putting testosterone into his veins day and night for at least four months!
The researchers needed to find a way to prevent the body from breaking down the testosterone so quickly. Through trial and error, chemists discovered how to alter the testosterone molecule so it would last longer.(1,2)
There are many kinds of anabolic steroids available to treat several disease states. In the past, anabolic steroids were taken from animal tissues for use in early experiments.(1) Today, anabolic steroids are chemically manufactured rather than being purified from natural sources.
