Medical tests: more is not synonymous with better

The diagnosis of any disease is based on three fundamental pillars. The first one is to talk to the patient to find out the discomfort or problems he/she presents, their duration, factors related to their appearance, as well as his/her medical history.

This is followed by the measurement of vital signs (blood pressure, heart rate, respiratory rate…) and a careful examination of the whole body by palpation and auscultation. Finally, based on all of the above, a diagnostic hypothesis is established and the necessary tests are indicated to confirm or rule it out.

This simple procedure, of obvious importance, is the axis around which medical practice should revolve. However, there is a growing tendency to abandon this approach and to base the diagnosis, prognosis and treatment of patients primarily on medical tests.

Why is this happening?

In many cases the physician does not have time and in other cases the physician considers that the traditional medical act can be replaced in whole or in part by analyses, ultrasound scans, CT scans, MRI scans, etc. In today’s world, technology has become a true idol to which many pay tribute.

Practically everyone has heard of genomics, mega-data, artificial intelligence, algorithms, precision medicine, etcetera. It is therefore common for patients to applaud what we could define as a “technological approach” to their medical care and consider that the more tests that are requested, especially if they are sophisticated and expensive, the better the care they are receiving.

What is more, on many occasions the patient goes to the doctor having first consulted with what has come to be called Doctor Google, if not after diving into crazy social networks, about his possible diagnosis and with the list of tests that in his opinion should be done, and which in certain cases he even demands.

The request for a large number of diagnostic tests can have many other origins, such as avoiding complaints and claims (so-called “defensive medicine”), the desire to be “complete” (we will look at everything) or even the desire to try out the “new machine”.

Why is more not necessarily better?

In very rigorous clinical studies it has been shown that unwarranted diagnostic tests are not only not beneficial to the patient, but can be harmful. The relationship between irradiation, nuclear accidents, atomic bombs and cancer is well known.

But beyond these extreme cases, a body CT scan causes as much irradiation to accumulate in the body as is due to so-called “background” irradiation, from the environment, over 5-7 years. At the opposite extreme, a chest X-ray is equivalent to “background” irradiation for about 5 days.

Nuclear magnetic resonance and ultrasound scans do not involve irradiation. Does this mean that CT scans, radioactive isotope tests or repeated x-rays should be avoided at all costs? Absolutely not.

In fact, diagnostic imaging techniques are one of the most important advances in medicine in recent decades (the discoverers of CT received the Nobel Prize in 1979) and are not only useful but in many cases essential. But they must be used well.

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Such tests can lead to complications and side effects, sometimes serious: allergic reactions, bleeding, visceral perforations, thrombosis and many others.

From another perspective, the indiscriminate practice of diagnostic tests can lead to the identification of trivial medical problems, totally asymptomatic, that do not compromise quality of life or life expectancy and do not require any treatment. These are what can be defined as “superfluous” or “exaggerated” diagnoses (overdiagnosis) which in turn lead to unjustified or unjustified treatment (overtreatment).

Both should be of equal concern to health authorities (the cost overruns of this malpractice are phenomenal), physicians and patients. Here we can only give a few examples. One of them revolves around cholesterol.

Most people with slightly high cholesterol without cardiovascular risk factors (overweight, smoking, hypertension, arteriosclerosis) do not need to take drugs. And in those who do present cardiovascular risk, the first measure is to increase physical exercise, give up smoking, and reduce weight. Many of these people, however, are prescribed anti-cholesterol drugs (the famous “statins”) immediately after being “diagnosed”.

Paradoxically, the medication can cause side effects (allergic reactions, headaches, swelling of the feet, heart rhythm disturbances) which in turn require medical attention. This brief section cannot close without mentioning, albeit briefly, PSA (prostate-specific antigen).

PSA is increased in cases of hypertrophy and tumors of the prostate gland, even when there are no symptoms. The massive and indiscriminate determination of PSA has led to a spectacular increase in prostate cancers, in fact, their detection. The difficulty lies in what to do in asymptomatic individuals with elevated PSA: to biopsy the prostate or not to do so; to intervene surgically in cases in which a tumor is confirmed? These questions are very important.

Keep in mind that removal of the prostate is not a minor intervention and can lead to permanent urinary and sexual function disorders.

Although this is not the place to discuss the treatment of prostate cancer, several studies have shown that in many cases fortuitously diagnosed prostate cancers with a good prognosis can be managed conservatively, without treatment and with periodic check-ups.


The reader who has had the patience to follow me this far may ask: How can I know whether a medical test is justified or not? Ethics requires that all medical acts be justified and that their benefits outweigh the possible drawbacks.

Therefore, the answer to the question posed can only be another question: Doctor, how will the test you are recommending change my diagnosis, prognosis or treatment?

Avoid the useless and superfluous, discuss the pros and cons of the different options, trust in the professionals and, of course, in the correctly indicated diagnostic tests and technology, as this is the best way to take care of your health.