Combatting tiredness: are blood tests a sensible first step?

In Western societies, it is common for people to complain of feeling tired or fatigued. Indeed, it is the second most common reason for patients to consult with their General Practitioner (GP), behind respiratory infections in first place.

It is of interest to know how GPs, as experienced doctors, handle patients complaining of fatigue. In an Australian study of 342 patients presenting with unexplained tiredness, the GP undertook blood tests in only half of the patients. Of the patients who got blood tests, only 3% had an abnormality detected. It is a medical rule of thumb that 80-90% of diagnoses are based on the history, rather than on examination or investigations, and the doctors in this study managed half of the patients without investigations. Another medical review concluded that tests for tiredness which the doctor did not deem essential could be performed mainly to reassure the patient – and maybe themselves as well!

In the Netherlands, a large group of patients with unexplained tiredness was randomised into a “blood tests” and a “no blood tests” group. Interestingly, the “no blood tests” patient was invited to re-attend four weeks later if they felt tests might be relevant, but only 24 out of 138 did so. Among the “blood tests” group, abnormalities were detected in only 14 out of 173 (8%). Four patients were diabetic, 3 patients were anaemic, 3 patients had mononucleosis and 1 had hypothyroidism – bear in mind that these conditions may have been strongly suspected on the basis of the patient’s histories. In another review of published studies it was concluded that physical illness was no more common in people complaining of tiredness than in those who did not! Depression was more common among the tired people.

Perhaps partly because access to medical care was restricted during the Covid pandemic, on-line blood tests “health MOT” companies have proliferated. A typical “fatigue work up” costs over £100. From the data above, the question as to whether this is money well-spent is surely rhetorical. Furthermore, normal blood tests may give false reassurance since the vast majority of the causes of tiredness do not show up in blood tests.

Some of the common causes of fatigue, which are not diagnosed by blood tests are as follows:

  • Psychological factors (notably depression and anxiety)
  • Psychosocial stress (e.g relationship or work issues)
  • Poor sleep
  • Obesity
  • Poor diet (spikes of blood sugar, followed by fatigue inducing falls)
  • Sedentary lifestyles
  • Caffeine (once excessive intake wears off)
  • alcohol
  • food intolerances
  • dehydration
  • shift work
  • post-viral syndrome

So, if you are one of the many people feeling unaccountably fatigued, what is the best course of action? We hope you appreciate that an “MOT” blood test approach is not sensible. We would advocate a full bold lifestyle assessment, including a detailed history (and relevant tests thereafter) leading to a comprehensive analysis of the underlying issues and a detailed treatment plan. Such a service is available at Temple Medical through the Temple Vitality programme.

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