The problem with DIY health test kits

Checking on your health from the comfort of your own home is a tempting prospect in the midst of the pandemic, but buying a self-test kit to use at home may just leave you with less cash and more questions.

Home testing kits may appear to offer an easy way to detect underlying issues or get peace of mind without having to visit your GP, but our research uncovered some worrying drawbacks.

We looked at six popular self-test kits, including diagnostic blood tests, fingerprick tests for cholesterol, blood glucose and prostate health, and pricey gut health tests, asking experts to assess them on factors including usefulness, reliability of the results and ease of understanding them.

We found that while many claim to help you detect deficiencies or disease, they aren't able to give the full picture. Worryingly, some had potential safety issues, while others over-promised what they could tell you without sufficient scientific backing.

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What are home health test kits and why use one?

Home self-test kits fall into two broad categories:

• Rapid result tests give near-instant results at home based on a sample of your blood, urine or saliva. The kit should include information on how to interpret results yourself.
• Lab-analysed tests involve you collecting and posting your sample to a lab for analysis and waiting to receive results, usually via email, an online dashboard or an app. They tend to be pricier, and some try and upsell private consultations or additional tests off the back of your initial test.

People tend to turn to self-test kits for peace of mind about a symptom or issue that is worrying them, but by and large, home test kits won't be able to give you a clear answer.

Knowing why someone is seeking a particular test is an important factor in the interpretation of results, which self-test kits can't take into account.

Lab-analysed tests might come with some screening questions for context, but this is still a poor substitute for a proper medical consultation. In fact, a recent study found that GP's gut feelings about patients play a key role in diagnosing cancer.

'Interpreting bloods is a real art and needs to be done in the context of why they were ordered and what else is going on,' a GP told us.

Another issue is that a self-test could falsely reassure you that everything is fine when it actually isn't. For two of the rapid-result fingerprick blood tests we looked at, our experts felt there was a risk of this happening.

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Home test kits: our verdict

SELFCheck Cholesterol Level Test, £14.99

Our experts felt that this test used an overly simplistic comparison of 'normal versus raised' total cholesterol and also failed to put this metric in context of other important risk factors, such as smoking.

Having your cholesterol measured by a doctor would give you a more detailed breakdown of different types of cholesterol and would use additional measures to determine risk of cardiovascular disease.

The included test leaflet itself caveats that a one-off test of this kind is 'not particularly meaningful'.

Boots Pharmaceuticals Blood Glucose Home Test Kit, £12.99

This test uses a relatively basic and old-fashioned method of placing a drop of blood on a diagnostic colour test strip.

It says it may help in the early detection of diabetes (by telling you your blood glucose levels), but it can't diagnose the condition.

Our experts found the results colour chart difficult to interpret and also worried that there was potential for false reassurance.

The instruction to simply repeat the test in a few days, even if you got a very high result, was flagged by one of the GPs as potentially dangerous.

The test doesn't mention other symptoms of diabetes, which may have prompted a person to take the test and therefore a normal result might stop them seeking further advice when they should.

SELFCheck Prostate Health Test, £14.99

This test says it can detect abnormal levels of prostate-specific antigen (PSA) in the blood, but this is an unreliable marker of prostate health and the test doesn't address the complications with this type of testing, nor the consequences of taking a PSA test.

Our experts were concerned that the cut-off level for 'normal' PSA used in this test is higher than NHS guidelines for men between 50 and 69, so there's a danger that men who would be urgently referred on the NHS would be told by this test that they have a 'normal' result.

It also says that men are recommended to get their PSA checked every year, which is not true. The NHS says there's currently no national screening programme for prostate cancer in the UK because the PSA test is not always accurate.

Medichecks Health and Lifestyle Blood Test, £61

Medichecks kits carry the tagline 'Know yourself. Inside out', which one of our experts thought was as an oversell, pointing out that in the case of the general health test we looked at, it's marketing to the worried well who might overestimate what the results can actually tell them about their health and what they can do with the information.

This test is billed as an overall health MOT, which essentially uses a range of blood tests, including kidney function, liver function, muscle health and some vitamin checks, to provide a snapshot of your general health.

You take a sample of blood at home (via a finger prick) and post it off to a lab for analysis, with results returned in a few days.

It gives you an online dashboard of results accompanied by what our clinical pathologist thought was an acceptably detailed explanation of what was being measured and what a normal, abnormal or borderline result might mean.

But our experts felt it could be hard to interpret the results if there's no specific health question in mind and that the combination of tests offered were of varying utility in flagging up a specific issue.

For example, the 'kidney health' check above omits some tests that would be needed to properly understand renal function. This is because some tests cannot reliably be done on day-old blood samples.

Gut health tests: Viome Gut Intelligence Test, £120 (plus £50 shipping, not included), and Atlas Biomed Microbiome Test, £149

If posting a stool sample for analysis doesn't deter you, you might be intrigued by what a microbiome test kit could tell you. But the truth is right now it's unlikely to be that useful.

The two microbiome tests we looked at, which aim to give you a snapshot of your gut health, provide lengthy reports crammed with highly technical language, alongside recommendations around what food you should eat and foods to avoid, and, in some cases, suggested probiotic supplements to take.

But, while it's true that there is exciting research going on about how the microbiome could help inform personalised nutrition advice and influence disease risk, the experts we spoke to said that this science is still in its very early days, so making detailed and specific personal recommendations is tricky.

Atlas Biomed gives you a risk prediction for five diseases, including Type 2 diabetes and Crohn's disease. But this might be misleading. The Guts UK charity says that while some microbiome test results might suggest that a certain condition is more likely, this is pure speculation and could cause unnecessary concern.

Viome gives you a contextual score on a number of specific microbial functions including 'flagellar assembly pathways' - the movement of microbes in the gut - and 'LPS Biosynthesis Pathways' (above) - the production of a pro-inflammatory molecule in the gut.

These are explained in quite scientific terms, many without accompanying advice on what to do about an average or poor score.

Our microbiology expert told us that neither of these functions are easily categorised as 'good' or 'bad', so it's hard to see how this information is useful.

Both companies suggest that people take a test every three months to track changes (costing hundreds of pounds a year), but experts told us it's unlikely to be possible to alter your microbiome in the time between tests.

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What the companies told us

• SELFCheck stated that 'all self-test diagnostics are tightly regulated regarding reliability, clinical information and usability in the UK' and that 'its products conform to these regulations'.
• Medichecks said its tests 'can help reassure customers or support them in making positive health and lifestyle changes or accessing further medical advice - such as a GP appointment'. It quoted a recent customer survey in which 91% of customers found their results useful. It also stood by its kidney function test, stating that: 'We are confident that our kidney function test gives sufficient resultsu2026 to signpost the customer to their doctor for further medical assessment should it be required.'
• Boots said its Blood Glucose Kit is compliant with regulations, but that it takes all feedback very seriously and will discuss the points we raised with the manufacturer. It also reiterated that these tests 'aren't a substitute for customers seeing their GP or for self-diagnosis of any medical condition, but can be a useful way of understanding more about their health before going to see their GP'.
• Atlas Biomed said that its test meets required compliance standards and assesses the level of disease protection, not risk, clarifying that just because our microbiome may share traits in common with a disease does not put you at risk of developing it. It also said that it has 'dedicated a lot of thought, time and resources to how the results are displayed, and the language used'.
• Viome told us that '150,000-plus customers have taken our tests and services, and 97% of them reported improvement in their symptoms after following Viome food and supplement recommendations, so unfortunately this report is not reflective of the positive experience of our customers'.

Which? verdict on home test kits

While some self-test kits may be a useful tool for providing remote health care - bowel cancer screening tests and sexual health self-test kits being successful examples used by the NHS - many private self-test kits don't serve such a clear purpose.

Our experts warned that self-test kits may leave you either unnecessarily worried or falsely reassured and none are a good substitute for a discussion with your GP.

In general, there isn't any real benefit to testing for something more often than you could on the NHS and any abnormal results from a self-test kit would ultimately send you to your GP anyway.

If something isn't offered by the NHS, such as microbiome testing, it's usually because there is no clinical decision to be made from receiving results, or the tests don't currently have a strong enough evidence base.

With most GPs offering remote consultations by phone during the pandemic, your best bet is to book an appointment to discuss your concerns so they can advise on whether a test is necessary.