Patients can now use a home-testing kit to discover whether they are at risk of developing the brittle bone disease, osteoporosis.

Similar kits are already available to test for allergies and susceptibility to heart disease.

And similar kits could soon be available for a wide range of diseases.

There are now hundreds of genetic tests that predict the likelihood of develoing inherited diseases.

Some companies in the US are already offering gene tests for breast cancer.

Health care revolution

In Britain some firms are already thinking of offering gene tests for heart disease and asthma.

The manufacturers are hailing the development as a revolution in health care.

But doctors are concerned that patients will miss out on valuable medical opinion, and that the tests could do more harm than good.

A private company is selling the osteoporosis test kit directly to the public.

All the patient needs to do is to send a urine sample back to the firm by post.

The company tests hundreds of samples each day.

Those that turn blue indicate a high risk of osteoporosis in later life.

The test results are sent back to the customer's GP, who then decides what treatment to offer.

Plethora of tests

Barrie Mellors, of University Diagnostics, a company that manufactures home-testing kits, claims that many tests will be made available direct to patients by the public sector.

He said: "The days of 'doctor knows best' are long gone.

"There is a plethora of tests coming through, and the cost to the NHS would be enormous."

Jill Ellison decided to take an osteoporosis test after her mother was diagnosed with the disease.

She said: "Having family members suffering and knowing that could have been prevented, I want to take positive action now to help myself so in later life I can be mobile and have my own independence."

Dr Vivienne Roberts is worried about the tests

Jill Ellison's GP, Dr Vivienne Roberts, fears that patients will be sold tests they simply do not need.

"The danger is that people who are over-anxious about their own health will go and have too many tests done.

"I think it would be better probably if they come and discuss it with their GP first of all, and for the GP to decide whether there would be a reason for them having the test done."

Professor Martin Bobrow, of the Human Genetics Advisory Commission, said: "If the test just tells you in 15 years' time you are going to develop some disease and there is nothing you can do about it, that information may not be very helpful to you at all - it may be rather unhelpful."