Doctor, are you blabbing on me?

Your medical records contain intimate personal information you would expect to be kept strictly confidential. But, for a fee, your GP will pass on details of consultations to private companies with a financial stake in your well-being.

Your medical records contain intimate personal information you would expect to be kept strictly confidential. But, for a fee, your GP will pass on details of consultations to private companies with a financial stake in your well-being.

Apply for insurance, a mortgage or job and your full medical history may be open to scrutiny by the insurer, lender or future employer.

If you have ever consulted about a sexually transmitted disease, stress or depression, it will be recorded in your notes. If you smoke, have had your cholesterol levels checked or had an HIV test, your insurer or future employer will soon know of it.

Insurance companies may also ask your GP whether aspects of your lifestyle could adversely affect your health, and request dates and details.

Your GP's report could affect your chances of getting a job. You may face more expensive life or critical illness cover, or income protection insurance, or even be turned down.

GPs must seek your "informed consent" before writing a report based on your notes. But refuse and your application for a job or insurance is likely to be rejected out of hand.

The Association of Community Health Councils, a patient pressure group, warns that few patients realise the personal nature of the information being passed on by their GP. Consent, it argues, is anything but informed.

GPs earn a fee for completing insurance forms, since the work falls outside NHS services. This is currently £30.10 for a report extracted from medical records, and £42.80 for a medical examination. But GPs don't do it for the money. Most see it as a tiresome demand on their time, and many are concerned that writing insurance company reports compromises their role as the patient's advocate.

Dr Laurence Buckman, a member of the GPs' Committee of the BMA, says insurance companies need to give customers a clearer explanation of what medical report writing involves. "Everything is recorded in your medical notes from birth onwards," he points out. "Even something that seems quite trivial to you may show patterns of behaviour that will alert the insurance company. Many patients don't realise that, say, having once had a Valium tablet could hit them very badly."

Dr Buckman says you should remember that you are entitled to see the report before it is sent. He adds: "If I think the report is going to be damaging I telephone the patient and ask if they realise what I'm going to write. Sometimes I don't think I should write the report at all."

Some groups of patients are well aware of the dangers - notably young gay men. At the peak of the Aids scare in the early 1990s, insurance companies' questions were increasingly intrusive. "Things have improved now, but many questions were then being asked about sexual history, HIV testing and so on," says Jack Summerside, health promotion officer for people with HIV at the Terrence Higgins Trust.

"Doctors often don't realise that if somebody is applying for a job they only need release details that concern their ability to do that job," Mr Summerside continues. "For example, they don't have to reveal that a health worker not involved in invasive procedures is HIV positive."

Insurance companies would expect to know, however. They argue that it is essential they retain access to information held on medical records. This allows them to charge high-risk clients more, rather than raising premiums for everyone.

"It is important for insurance companies to get as full a picture as possible of the risks that they are insuring," says Malcolm Tarling, spokesman for the Association of British Insurers.

Insurance companies may also request that you release the results of any genetic tests you have taken for certain conditions, including Huntington's disease, myotonic dystrophy, the early-onset form of Alzheimer's disease and rare inherited forms of cancer. However, they cannot ask you to undergo a genetic test.

Your medical records will shortly be available in a number of new electronic formats. By the end of this year encrypted versions might be passed around the NHS intranet. Personal medical information is already held by health authorities, local councils, universities, drug companies and medical schools, and GPs are worried that confidentiality is increasingly lax.

"From a position of having been the guardian and standard-setter of confidentiality, medicine has now fallen far behind the highest standards and routine practice now fails to fulfil the basic principles of the data protection legislation," Dr Iona Heath, chair of the RCGP Medical Ethics Committee, warned in June.

Nobody is suggesting you hide health problems from your GP for fear they will prejudice an insurance or employment application. Your doctor must be aware of all your conditions before he or she can safely prescribe treatment.

Nor should you ask your GP to supply false information. They could face disciplinary action, and such information, or non-disclosure, will invalidate an insurance claim.

But you can exercise your right to see what is written about you to a third party. Under the 1988 Access to Medical Reports Act, you may see reports sent to an insurance company or employer concerning you.

The 1990 Access to Health Records Act gives you the right to see your health records. Your GP can charge a £10 fee for viewing information more than 40 days old, with further charges to cover postage and photocopying.

You can request that factual inaccuracies be corrected, but the doctor is not obliged to accept your opinion. However, you can append a statement on any disputed information.