It's now possible to get a self-test kit for just about any ailment - including cancer and HIV - over the internet. But are they effective? Roger Dobson investigates

Worried about cancer, troubled by genetic diseases, or concerned about the menopause? Time was when only a visit to a doctor offered the prospect of a diagnosis, but not any more.

The internet is awash with DIY tests on sale for as little as £1, promising diagnoses for asthma, diabetes, cancer, flu, fertility, heart diseases, amniotic fluid leak, HIV, genetic disorders, and much more.

Researchers at the University of Birmingham, who collected data on 167 self-tests advertised by 19 retailers, say that while self-tests do have potential benefits, including privacy, speed and convenience, they may also have potential downsides, including stress caused by false-positive results, and risks associated with false-negative results.

The self-tests they identified required samples of blood, stool, saliva, semen, urine or vaginal discharge: "The samples were processed at home with results available in minutes or sent to a laboratory for processing with results returned by e-mail or post after several days,'' say researchers.

"We are starting to gain an understanding of who is using self-tests, how and why they are being used, and their impact on the public and health services. We think that this is essential as a wide range of self-tests are likely to continue to be available," says Dr Angela Ryan, who led the study.

Eighty per cent of the tests in the Birmingham research cost less than £30, but there are others available which are more expensive. A report from the US Federal Trade Commission shows that gene tests now cost up to £600.

In its advice to consumers, the American Food and Drug Administration urges caution when buying home-use tests on the internet: "Although many good home-use tests are available online, others may not work or may even be harmful. If you think that you have a medical condition or disease, see your doctor."

MENOPAUSE

COST

£2 to £14

WHAT IS IT?

Designed to indicate whether or not a woman is in the menopause.

WHAT DOES IT DO?

Home-use test kits measure follicle-stimulating hormone or FSH in a sample of urine. FSH is a hormone produced by the pituitary gland, and levels increase temporarily each month to stimulate ovaries to produce eggs. Levels also increase when a woman goes into the menopause. Tests will detect FSH, but do not necessarily detect menopause. The test can be affected by the time of day the urine sample is collected, by HRT and the Pill, and by how much water has been drunk before the test.

SHOULD YOU BUY IT?

"Do not stop taking contraceptives based on the results of these tests because they are not foolproof and you could become pregnant. You should not assume that a negative test means you have not reached menopause, there could be other reasons for the negative result. You should always discuss your symptoms and your test results with your doctor," says the US Food and Drug Administration.

GENETIC TESTING

COST

£150 to £600

WHAT IS IT?

A wide range of at-home genetic tests are designed to examine genes and DNA to see if they indicate a predisposition to particular diseases or disorders.

WHAT DOES IT DO?

At-home tests usually require a blood sample or a swab from inside the cheek, which is then sent to a laboratory for analysis.

SHOULD YOU BUY IT?

Genetic testing provides only one piece of the picture. Environmental factors, lifestyle and medical history also affect the risk of disorders occurring. "At-home genetic tests have risks. Consumers are vulnerable to being misled by unproven or invalid tests. Without guidance, they may make important decisions about treatment or prevention based on inaccurate, incomplete, or misunderstood information," says the US National Library of Medicine.

OSTEOPOROSIS

COST

£43 to £49

WHAT IS IT?

Tests that look for signs of the age-related bone disease . One in two women and one in five men will break a bone at some time, mainly because of osteoporosis.

WHAT DOES IT DO?

Compounds released when bone breaks down can collect in the urine. An at-home sample of urine is sent off for laboratory examination.

SHOULD YOU BUY IT?

"Over-the-counter urine tests are not that useful for the individual. They have a role to play in research and specialist environments, but they cannot diagnose or assess the risk of osteoporosis," says the National Osteoporosis Society.

PSA- PROSTATE CANCER

COST

£2 to £28

WHAT IS IT?

PSA tests measure levels of prostate-specific antigen, a protein produced by the prostate gland, whose job is to keep semen that carries sperm in a liquid form.

WHAT DOES IT DO?

PSA levels can help a doctor diagnose and manage prostate problems, but they are not necessarily an indicator of prostate cancer or any other disease. Levels rise naturally with age. Researchers at Stanford University found that the PSA test indicates nothing more significant than the size of the prostate

SHOULD YOU BUY IT?

"The PSA test should not be referred to as the test for prostate cancer, as only in a minority of cases is it diagnostic of cancer. Testing kits give false reassurance or cause undue anxiety. More often an abnormal PSA is indicative of other, non-cancerous problems. We would dissuade, at all times, the use of home-testing kits for prostate cancer," says the Prostate Cancer Charity.

CHOLESTEROL

COST

£3 to £75

WHAT IS IT?

Tests for levels of blood cholesterol and in some cases, triglycerides. Some research advises everyone over the age of 20 to be tested every five years.

WHAT DOES IT DO?

A lance is usually provided and you prick your finger to get a drop of blood, which is put on to a piece of treated paper that changes colour according to the level of cholesterol.

SHOULD YOU BUY IT?

"This test is about as accurate as the test your doctor uses, but you must follow the directions carefully. Total cholesterol tests vary in accuracy from brand to brand. Talk to your doctor if your test shows that your cholesterol is higher than 200mg/dL," advises the US Food and Drug Administration.

BOWEL DISORDERS

COST

£1 to £16

WHAT IS IT?

Home-use test kits to measure the presence of blood in faeces, which can be an early sign of abnormal growths or polyps, or cancer in the colon.

WHAT DOES IT DO?

Different techniques are used. In some at-home tests, a special solution is added to paper cards to see if they change colour when exposed to faecal material.

SHOULD YOU BUY IT?

While the tests can be accurate, as long as the directions are carefully followed, a positive result does not necessarily mean disease. "A positive result means that the test has detected blood. This does not mean you have tested positive for cancer or any other illness. False-positive results may be caused by diet or medications,'' says the FDA.

CHLAMYDIA

COST

£15 to £61

WHAT IS IT?

Tests for chlamydia , a sexually transmitted infection. A common, treatable condition, which is estimated to affect one in 12 women between 16 and 24.

WHAT DOES IT DO?

Involves testing a sample of body fluid from a swab or urine to determine whether Chlamydia trachoma bacteria are present. Can be wholly done at home, or samples sent off for analysis.

SHOULD YOU BUY IT?

Researchers at Johns Hopkins University in Baltimore found the tests they looked at, which involve laboratory analysis, effective and popular. "Home-test kits provided young women with a safe and effective means for protecting their sexual reproductive health. The home-test kits offer physicians and nurses another tool in efforts to reduce the spread of chlamydia,'' they say.

CANCER

COST

Up to £400

WHAT IS IT?

Tests that claim to be able to detect a wide range of cancers (far right) including breast, ovarian, lung, uterine, prostate, testicular, colorectal, pancreatic, liver and stomach.

WHAT DOES IT DO?

Said to look for biological markers in the blood that indicate malignancies.

SHOULD YOU BUY IT?

"No single blood test can detect all cancers, and people should be very wary of websites advertising such tests. Cancer Research UK runs a patient information website, CancerHelp UK - www.cancerhelp.org.uk - where people can find reliable information about cancer and about the tests used to detect it. If anyone is worried about any changes in their body, they should visit their GP as soon as possible,'' says Dr Anthea Martin of Cancer Research UK.

HIV

COST

£9 to £11

WHAT IS IT?

Home-use collection kits to detect whether or not you have human immunodeficiency virus.

WHAT DOES IT DO?

Looks for antibodies to HIV in the blood, which can be a sign of infection. Other varieties test for the presence of the virus via the oral fluid .

SHOULD YOU BUY IT?

A cautionary tale from the US Food and Drug Administration: "Sally was afraid that she had been exposed to HIV. She decided to purchase her HIV test from an internet source. She took the test and was distraught to find that the result was positive. After several weeks, she went to her doctor who used a more sophisticated method - and the result was negative. Sally did not have HIV."

REDUCED FERTILITY/INFERTILITY

COST

£2 to £32

WHAT IS IT?

Tests that measure male fertility.

WHAT DOES IT DO?

Male infertility home test kits used with semen samples can show when sperm cell counts fall below a certain level, a potential indicator for male infertility.

SHOULD YOU BUY IT?

"A positive test is no guarantee of infertility, meaning that other factors may be involved. Users should confirm test results with their physicians,'' says the US Food and Drug Administration.

Online test tips

* If you think that you have a medical condition or disease, see your doctor or healthcare professional.

* Many tests promise in-home results, but most should be followed with a second, more sophisticated laboratory test to confirm the results.

* Check the test out with your doctor or healthcare provider.

* Be wary of tests that claim to diagnose more than one illness.

* Be wary of "home brew" tests - those that are made by only one laboratory.

* Don't be taken in by a professional-looking website.

* Avoid websites with no telephone number.

* Avoid websites that talk about new cures and miracle cures.

* Beware of claims that the test complies with all regulatory agencies.

Source: Food and Drug Administration

www.fda.gov/oc/buyonline

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