Can you trust home health test kits or is a visit to your GP still the best option?
From cholesterol to cancer, there's a DIY home test for almost everything these days - but are they really accurate? Lisa Salmon investigates
Technology has spread into so many areas of our lives, perhaps it was inevitable that this would eventually include medical testing. Just last month a new cervical cancer risk test was launched, claiming to offer women "a comfortable and private alternative to smear tests" - but doctors warn that such tests are definitely not an adequate replacement for attending cervical screenings.
So which tests - if any - are worth doing?
"There are a bewildering array of self-tests out there, and the great difficulty patients have is knowing whether the test is appropriate for them, if they can trust the results, and what do the results mean for them," says Dr Helen Stokes-Lampard, spokesperson for the Royal College of GPs.
"There are many tests that don't have clear yes and no answers, and frequently give you a borderline result, so what do you do with it? That's when you need a bit of medical help and expertise."
"If you're worried enough to buy a test," she adds, "then perhaps you should think about going to see your GP instead."
Here, she offers her advice on a selection of self-tests.
Human papilloma virus (HPV)
The most common cancer in women under 35, approximately 3,100 women in the UK are diagnosed with cervical cancer each year, and 99.7% of cases are caused by HPV.
Despite a nationwide screening programme for women aged 25 and over, only 66% of younger women and 80% of older women attend, and new research by GynaeHealth UK found that 1.1 million have never had a smear test, citing pain, embarrassment and struggling to get to an appointment as the main reasons.
Home screening kits don't detect cancer, but they could detect HPV - which can sometimes, though not always, lead to abnormal cell changes and cancer. The tests involve women taking a vaginal swab and sending it off for analysis.
Dr Stokes-Lampard warns: "It is definitely not an adequate replacement for cervical screening via the NHS national programme, and the national programme is already doing HPV testing as part of the process.
"I would always urge women to attend for cervical screening as per the national guidelines, as this provides the most comprehensive testing available and is tried and tested."
Sexually transmitted infections
Sexually transmitted infections (STI) such as chlamydia can be symptomless, but could cause infertility if left untreated. Tests can be done through GP surgeries or at sexual health clinics, but a variety of home-testing kits are available, usually using a swab test for women and a urine test for men. Some give instant results, others are sent off to laboratories.
Dr Stokes-Lampard warns that if people want to use a home-testing kit, they should ensure it's from a British manufacturer, as if a test comes from abroad, there are no assurances that data is protected or that the result is genuine.
"While I would always ask people to get tested by their GP or local sexual health service, if people are too embarrassed, then using a home-testing kit from a reputable manufacturer, having read the instructions properly, is a second best option."
If you've been unsuccessfully trying to conceive for at least a year, NHS fertility tests can be performed, or you can try a private clinic. Various home tests are also available, testing either blood or urine for ovarian function or ovarian reserve hormones.
Dr Stokes-Lampard warns: "The number of eggs you store is quite specialist territory, and I'd be wary of trusting your future fertility to a (home) test kit.
"If you're not eligible for NHS fertility treatment, then it's better to go to a reputable fertility service provider to have counselling, and appropriate testing that you know is right for you."
These tests involve checking blood through a home finger-prick for prostate specific antigen (PSA), which is released by some prostate cancers.
While some men with prostate cancer will have a high PSA reading, many won't. Plus, some men with a completely normal prostate will have a high PSA reading, and Dr Stokes-Lampard says any test results should be considered in conjunction with all other symptoms, and a rectal examination by an expert.
"The test in isolation is a very weak test," she stresses.
"It isn't specific or sensitive enough, which is why we don't have a national NHS screening programme using the PSA test. If a test was reliable enough to use on its own, then the NHS would be doing it.
"These tests in isolation can be misleading, or even worse they can provide a false reassurance, letting people think they haven't got a problem when they actually have.
"It's dangerous to have false reassurance from a test and then leave it months or years before you go to see someone, by which time a lot more damage could have been done."
Bowel cancer is the third most common cancer in the UK, with the second highest cancer mortality rate. All men and women aged 60-74 are invited to have an NHS bowel cancer screening test, which involves being sent a kit and sending off three stool samples in the post.
Home-screening kits are also available and, like the NHS tests, involve testing for blood in the faeces. Some require samples to be sent off in the post, while others boast instant digital results.
"If people don't want to wait for their turn on the national screening programme, or if they're younger and wish to purchase a test, they can do that, and it's a helpful test to a certain extent," says Dr Stokes-Lampard.
"But it's only a rough guide and I would never want anybody to rely on one of those tests - if you're worried you might have bowel cancer, then you really need to be speaking to a healthcare professional and not relying on the results of one test alone."
High blood pressure
Various automatic home blood pressure testing devices are available, although the charity Blood Pressure UK warns it's important to choose a home monitor that's been clinically validated.
"As long as people read the instructions, do it properly, take their time and repeat the reading, then home blood pressure testing can be really helpful," says Dr Stokes-Lampard.
However, if your results are high, ensure you follow up with your doctor for advice and, if deemed necessary, treatment.
Free cholesterol blood tests are available on the NHS every five years for those aged 40-75, and every 12 months if you're on cholesterol-lowering medication or have a family history of the high cholesterol condition, familial hypercholesterolemia (FH).
But although six out of 10 UK adults have raised cholesterol, Heart UK doesn't endorse home-testing, as it's a skilled job and the results can be affected by the way in which the test is performed.
"Cholesterol testing in isolation isn't terribly helpful, unless you've got a strong family history," explains Dr Stokes-Lampard.
"Having raised cholesterol is just another risk factor for health problems, like being overweight, smoking or not doing enough exercise.
"I would urge people to lead a healthier lifestyle, rather than worrying about testing for specific cholesterol numbers.
"And if your test comes back as normal, it doesn't mean you shouldn't be looking after yourself and eating a healthy diet," she adds.