When ‘routine blood tests’ do more harm than good

Updated 19 December 2022

Back in May 2017, I conducted a Deep Dive webinar, ‘Understanding Your Blood Test Results’, for members of my EmpowerEd health and nutrition education program. You can watch the webinar and download the fully-referenced slides by taking up the 1-month free trial of EmpowerEd here.

Before diving into the most common blood tests (full blood count, UEC/LFT, iron studies, thyroid function studies and so on) and what high or low readings on each of these might mean, I discussed an article that was published in the British Medical Journal titled ‘Should we abandon routine blood tests?’

Although the article referred specifically to routine blood tests ordered for hospital patients (secondary care), the concerns raised by the authors are just as relevant to primary care settings, for example, a GP appointment.

I’m frequently asked by new clients, “What blood tests should I have before I come to see you?” My usual response is, “I won’t know which tests might be helpful until I actually speak to you and find out more about what’s wrong with you, as well as what you’ve been tested for in the past.”

This is what the authors of the BMJ article mean when they write,

“Historically, blood tests in secondary care were requested for defined indications and only after a detailed clinical history and examination of the patient.”

Should we abandon routine blood tests?

They contrast this thoughtful approach to test requests in the past, with the current situation:

“Requesting a standard battery of blood tests without due regard to clinical indication has become the norm—with no distinction made between patients with a variety of presenting complaints, from chest pain to fractures.”

Should we abandon routine blood tests?

You might be wondering what possible harm might come from routine blood tests, apart from having to have a needle in your arm, and losing a little blood volume! Isn’t it always better to have more information?

No, argue the doctors who wrote the article.

For starters, blood tests cost money to perform, and although routine blood tests are bulk billed under Medicare in Australia (and covered by the National Health Service in the UK, where the BMJ article’s authors hail from), thus shielding the patient from their true cost, the reality is that it’s taxpayers who foot the bill. Healthcare costs are rising inexorably every year, and money spent on unnecessary tests is money diverted from more worthwhile applications.

I for one would rather see schools able to purchase new computers without having to hold a bake sale, than have hundreds of thousands of dollars wasted on running tests that don’t provide any clinically useful information, which would seem to be the case if “up to 60% of abnormal investigations documented in medical notes do not lead to further investigation”.

For seconds, ordering a standard battery of tests undermines clinical judgment. It’s often an excuse for not spending adequate time actually talking to the patient and examining them. As students, health care providers (both doctors and naturopaths) are taught ‘differential diagnosis’ – that is, how to whittle down the long list of possible diagnoses that match a patient’s symptoms, to a short list of likely diagnoses that may require further testing to confirm.

For example, a headache may be caused by anything from dehydration to a brain tumour, but it would be extraordinarily irresponsible to send every patient who had a headache for an MRI scan to check for tumours!

I’ve seen many clients over the years who bring along reams of past test reports, most of them with results in the expected range. In practically all of these cases, the client either has vague symptoms such as fatigue or stomach discomfort, or a slew of symptoms affecting multiple body systems.

And in practically none of them has any practitioner they’ve seen in the past, ever asked them about what they eat, how much sleep they get and what’s going on in their lives. More often than not, improving their diet and lifestyle habits and handling their emotional and psychological difficulties either gets rid of their symptoms altogether, or reduces them to the point where carefully selected tests – rather than a battery of ‘routine tests’ – are likely to produce useful information about the cause of their remaining concerns.

Finally, ordering ‘routine bloods’ results in overdiagnosis – the identification of ‘abnormalities’ or ‘diseases’ that will never actually cause symptoms or result in premature death – and overtreatment – medical or surgical care that isn’t actually required, and may result in psychological, financial and physical harms.

This video of the brilliant (and very funny) Dr H. Gilbert Welch clearly explains overdiagnosis and overtreatment:

I’ve seen plenty of examples of this in my practice:

• Men whose ‘routine’ PSA testing resulted in a diagnosis of prostate cancer (generally a slow-growing cancer which can be often be managed using lifestyle modification) for which they were aggressively treated, resulting in urinary incontinence, erectile dysfunction and bowel damage from radiation treatment;
• Women whose ‘routine’ scan detected thyroid cancer (again, generally a slow-growing cancer for which the death rate has held steady over the last few decades while the incidence has increased dramatically, indicating substantial overdiagnosis) resulting in surgery, radiation treatment and a lifetime of thyroid hormone replacement therapy; and even
• A woman whose ‘routine’ blood tests revealed elevated levels of a marker of autoimmune disease, for the ‘treatment’ of which her doctor prescribed a highly toxic medication, specifically contraindicated during breastfeeding, even though the woman had absolutely no symptoms and was currently breastfeeding her baby!

Recently, in a Facebook group to which I belong, a woman whose ‘routine’ blood test had detected low ferritin (iron stores) reported that her doctor had prescribed an iron supplement, although she had no other blood markers of iron insufficiency, no symptoms of iron deficiency, and a perfectly normal haemoglobin level. Iron supplements are not without harms, and the decision to supplement with iron should be carefully considered, and definitely not based on a one-off blood test.

It’s important to remember that lots of perfectly healthy people live outside the reference ranges printed on blood test reports. For example, I have several clients whose ferritin levels have been in the ‘iron depleted’ range for over 10 years, yet they’ve never developed anaemia or any symptoms indicating inadequate iron status. Conversely, plenty of unhealthy people live inside reference ranges; everyone knows at least one junk food-munching couch potato whose cholesterol level and blood pressure are ‘perfect’!

The bottom line is, if you have no symptoms of illness, and don’t already have a diagnosed condition such as type 2 diabetes or cardiovascular disease which requires regular monitoring, you don’t need ‘routine’ blood tests – with a couple of exceptions, such as monitoring serum vitamin B12 levels if you’re on a plant-based diet and haven’t been consistent with your supplementation. Furthermore, having those tests may do you more harm than good.

If, on the other hand, you have symptoms that don’t respond to intelligently-directed lifestyle changes, or that worsen rapidly, then get to a doctor or hospital and have all the (clinically indicated, rationally chosen) tests you need to find out what’s wrong with you.

Would you like to learn more about what your blood test results actually mean, and what you should do about them? The recording of the ‘Understanding Your Blood Test Results’ webinar is available to view in the EmpowerEd members’ area, along with dozens of previous webinar recordings on topics such as cancer screening, bone health, gluten and overcoming sleep problems, as well as monthly Ask Robyn sessions which cover topics from the low FODMAPs diet to HPV vaccines to hair loss! Your first month of membership is free, so what are you waiting for? Register for EmpowerEd today!