Tetrahydrogestrinone

Injecting steroids can damage health

A drug called tetrahydrogestrinone may be at the centre of one of the biggest doping scandals ever to hit the world of athletics.

It is believed that up to 20 American athletes tested positive for the drug at June's US championships and in 100 later out-of-competition tests.

BBC News Online examines why so many people appear to have used the drug.

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What is tetrahydrogestrinone?

It is a new, specially designed anabolic steroid which has been tweaked by chemists to make it undetectable under normal testing.

However, experts have now developed a test which can pick up signs that the drug has been used.

What are anabolic steroids?

They are drugs that are usually synthesised from the male reproduction hormone testoterone.

They have been banned by many sports because of their danger to health.

Their exact effect on the body is still a matter of scientific debate.

Why do sportsmen take them?

Anabolic steroids can improve the body's capacity to train and compete at the highest level.

They reduce the fatigue associated with training, and the time required to recover after physical exertion.

They also promote the development of muscle tissue in the body, with an associated increase in strength and power. This is achieved by stimulating the production of protein in the body.

However, some of the increased muscle bulk may be due to the laying down of water and minerals, so the increase in strength may not be as pronounced as expected.

What are the risks associated with anabolic steroids?

Anabolic steroids promote the growth of many tissues in the body by stimulating the release of the hormone testoterone.

By disturbing the body's equilibrium, anabolic steroids can potentially cause damage to many of the body's major organs, particularly the liver, which has to deal with breaking down the compound.

There is also a significant risk of damage to the heart, which is made of muscle tissue.

Anabolic steroids can lead to an expansion of the cardiac muscle, which can cause heart attacks.

The drugs also promote the growth of bones, particularly facial bones such as the jaw, and the teeth.

There is also an increased risk of cancer.

Other side effects include:

The development of inappropriate sexual characteristics such as breasts in men, and facial hair in women

A deepening of the voice

Baldness

Male impotence