Testing to excess

Testing to excess
Science of Life


A ripple of excitement recently ran through the news media with the announcement that a blood test to detect cancer is under active development. Such a test would undoubtedly be a great boon, enabling very early detection of cancer when treatment has the best hope of success. New medical tests are constantly being developed that can detect an ever broadening range of diseases and conditions, including a widening battery of tests to detect defects in the developing foetus in the womb.

So, in order to be on the safe side why not get tested for everything, including testing the foetus when pregnant? Indeed this notion is becoming increasingly popular in America and will probably spread to this side of the Atlantic. But, the notion of testing for everything is not a good idea, as explained, for example, by Dr Jamie Wells in the Bulletin of the American Council on Science and Health, September 18, 2017.

Before I go any further I should strongly emphasise that anyone deciding on what medical tests to take should make all such decisions in full consultation with their GP and/or medical consultant. The medical experts can advise on the appropriate testing, reliability and power of the tests and interpretation of the results. Sharing decision-making with your medical professional will ensure that you are fully informed and have reasonable expectations and this joint approach will generally produce superior outcomes.

Of course modern medical tests are extremely useful and we should avail of them. Like many people of my age, I keep an eye on my cholesterol, blood sugar and so on, by having a blood test done every six months and I also monitor my blood pressure. But we must remain sensible about testing.

As Dr Wells advises, undertaking widespread medical testing in an attempt to answer all ‘what ifs’ and to cover all possibilities is a bad idea that usually induces unnecessary fears and inappropriate worries. And excessive worry about what may happen weakens our ability to cope when something bad does actually happen, particularly if one of our tests had indicated that this would not happen.

Anyway, the idea of ‘ruling out everything’ by extensive testing is a fallacy. Tests do not produce certainty, rather they indicate probabilities that this or that outcome will happen, and these probabilities change, for example over time, with aging and with medication use and lifestyle changes. Even if you undergo the most extensive series of tests, some/many things will remain untested and the results you receive will only reflect your condition at the actual time of testing.

Dr Wells cautions specifically against undertaking wide spectrum blood allergy testing, especially in the absence of defined symptoms. For example, such tests may indicate you are allergic to dairy products and to cat-hair, despite your experience of having no symptoms when you eat dairy products and despite having a trouble-free relationship with your cat. If you now decide to avoid dairy products because of the allergy test results you risk missing out on valuable/essential nutrients.

People can get funny ideas about what constitutes ‘healthy’ food. For example, people who have coeliac disease have an auto-immune reaction to wheat protein called gluten and they sensibly avoid foods that contain gluten. Supermarkets and restaurants now offer quite a range of gluten-free foods.

But many people who are not coeliac also choose to eat gluten-free foods thinking they are healthier than gluten-containing foods. This notion is scientific nonsense and a non-coeliac person who avoids eating gluten is simply missing out on the nutritional value of this protein.

For many years now it has been common practice to routinely screen men aged over 50 for prostate cancer, or susceptibility to it, using the prostate-specific antigen (PSA) test. But in 2012 a Preventative Services Task Force that advises the US government came out against routine PSA screening, citing evidence that it may do more harm than good.

Prostate cancers are often slow-growing, and so may never advance to the point of becoming life-threatening. This means men diagnosed with early prostate tumours may be unnecessarily subjected to radiation treatment, surgery and other treatments that can cause side-effects such as incontinence and impotence.

Men diagnosed with small prostate tumours that are not aggressive may now be offered the option of ‘active surveillance’ of the tumour over time by PSA testing and perhaps biopsies of the tumour, rather than going ahead straight away with radical treatment. Of course it is vital that the patient make all decisions in this area in the closest consultation with his medical consultant.

Now to the question of testing the developing embryo in the womb for defects and abnormalities. A growing battery of tests is available and this will undoubtably become ever more comprehensive as time goes on. We already know that in countries where abortion is readily available many developing babies diagnosed in the womb with significant problems are selectively aborted. For example, in the UK 90% of developing babies diagnosed with Down syndrome are aborted.

Wells points out that, as with many other conditions, there is a spectrum of impairment in Down syndrome. Many people think all people with Down syndrome are severely limited and quite sick, but this is a misperception. Down syndrome children are at higher risk than non-Down syndrome for certain cardiac problems but many Down syndrome children are not so affected and many that are can be effectively treated.


The average Down syndrome life expectancy has increased in recent times and is 50+ years today; most Down syndrome people self-report that they lead happy and contented lives. Furthermore, parents of Down syndrome children enthusiastically attest to the many blessings and joys their children bring to the lives of their families and to the wider world.

The risk with all this extensive medical testing is that we let fear rule our lives. We are developing a culture where only perfection is acceptable and we are weakening/disabling our self-belief about what we can or cannot handle in life. Life is inherently unpredictable to a significant extent and so is parenting. By over-concentrating on ruling out every last possibility that any ill will afflict us we may only succeed in choosing to live narrow fearful lives.

William Reville is an Emeritus Professor of Biochemistry at UCC.