When More Health Testing Makes You Less Healthy

There is an engineering concept that applies surprisingly well to medicine: the best part is no part, and the best process is no process. During medical school and my training as a junior doctor, this idea was drilled into me in a clinical form: sometimes the best test is no test, and the best treatment is to avoid an unnecessary one.

That sounds counterintuitive, especially in a world where longevity clinics are growing fast and offering ever-expanding panels of tests. The pitch is compelling. The more data you gather, the earlier you can catch problems and fix them.

The problem is that more testing can lead to worse outcomes. It can create harm that would never have happened if we had done less.

The South Korea Thyroid Cancer Story

If you want to understand how this happens, look at what occurred in South Korea after 1999.

The number of thyroid cancer diagnoses exploded. In 1999, there were 6.3 cases per 100,000 people. By 2009, it had jumped to nearly 48 per 100,000, more than a sevenfold increase.

At first glance, you might think something environmental changed and suddenly caused thyroid cancer rates to skyrocket. That is not what happened.

Researchers concluded that the spike was driven by screening, not disease. A government-funded cancer screening initiative led to widespread ultrasound screening of the thyroid. Doctors simply found many cases that had been there all along.

So did earlier detection save lives? No. Mortality from thyroid cancer stayed about the same.

What did increase dramatically was surgery. By 2012, around 11,000 people were getting thyroid surgery each year, compared to about 1,000 in 2001, with no meaningful change in death rates. Many of those surgeries were unnecessary.

A likely explanation is overdiagnosis. Some thyroid cancers grow so slowly that they would never cause symptoms during a person’s lifetime. Finding them does not help, but treating them can cause harm.

Thyroid surgery carries real risks, including damage to the laryngeal nerve (which can affect speech and swallowing), infections, and bleeding. When you scale that harm across thousands of unnecessary procedures, the public health impact becomes clear.

The Full Body MRI Problem

This same pattern shows up in modern longevity clinic trends, especially full body MRI scans.

Again, the logic sounds right. Catch something early before it becomes a crisis.

Sometimes a scan does catch a dangerous cancer. But it also frequently finds something else.

High-resolution imaging like CT scans and MRIs often uncover incidental findings, meaning unexpected abnormalities that are unrelated to the reason for the scan. These are extremely common, showing up in roughly 20 to 40% of scans.

If you are scanning a healthy person with no symptoms, almost everything you find is incidental by definition.

The question becomes: what do we do with all these findings?

Incidental Findings and the Cascade of Care

In practice, incidental findings often trigger what has been called a cascade of care. One unclear finding leads to more tests, then more follow-ups, then sometimes biopsies or procedures. Each step has costs and risks.

A good example is incidental lung nodules.

One study looked at people undergoing scans for plaque in the arteries. In 479 people, 81 (about 18%) had small lung growths discovered incidentally. None were cancer. But some people still needed additional imaging or biopsies to confirm that.

Biopsies are not harmless. They carry risks including bleeding, infection, and injury to nearby structures. Many of these abnormalities never needed intervention in the first place.

This is one of the most counterintuitive lessons in modern medicine: detecting more does not automatically improve outcomes. In some cases it increases harm and does not save lives.

This is why expert bodies like the American College of Radiology do not endorse total body screening for asymptomatic patients without clear risk factors. Their concern is straightforward: it leads to non-specific findings, unnecessary follow-ups, and significant expense without proven benefit in prolonging life.

Why “Just Ignore It” Does Not Work

Some people argue that you can do the scan and ignore harmless findings.

In reality, that is psychologically difficult. If someone is told, “We found a lump on your pancreas,” even with reassurance that it is likely nothing, most people will want certainty. That means further imaging and often biopsies.

Once you start the process, it is hard to stop, even when the probability of serious disease is low.

It Is Not Just Imaging

Longevity clinics do not only sell scans. Many also offer massive lab panels, sometimes 160+ blood tests.

Some tests are genuinely useful and actionable, like LDL cholesterol or ApoB. Many others are not clinically meaningful in healthy people and are mostly marketing, designed to create anxiety and justify expensive follow-ups.

The Prostate Cancer Screening Dilemma

Prostate cancer is a classic example of why more screening is not always better.

It is common, and many men who have prostate cancer will never develop symptoms or die from it. If they were never screened, they would never know it was there.

If screening detects cancer, it can lead to biopsies and treatment. Those interventions can cause significant harm, including erectile dysfunction and incontinence. Even biopsies have adverse effects and a small increased risk of serious complications.

Sometimes treatment is necessary and life-saving. But there are also many cases where treatment is done for cancers that would never have caused harm.

That is why the U.S. Preventive Services Task Force concluded there is only a small potential benefit for routine screening in men aged 55 to 69, with substantial risks. In practice, this requires individualized decision-making, not blanket testing.

Paying for Unproven Fixes to Unproven Problems

Another example is the emerging trend of filtering microplastics from blood. One clinic reportedly charges £10,000 for the procedure.

The problem is that scientists do not yet know what levels of microplastics are harmful, what target levels should be, or whether these procedures reliably reduce microplastics long-term. There is also an irony: procedures often use plastic tubing, which itself can shed microplastics.

This is a perfect example of spending significant money on interventions where the problem is not well-defined and the fix is not proven.

The Right Approach: Evidence-Based Screening

The takeaway is not that screening is bad. It is that screening has tradeoffs.

You can go wrong in two directions:

• Too much healthcare: aggressive screening in people without symptoms, where harms outweigh benefits

• Too little healthcare: skipping proven screening where benefits clearly outweigh harms

The best way to navigate this is to rely on evidence-based guidelines from expert bodies that evaluate outcomes, not just detection.

For example, cancer screening for breast, colorectal, cervical, and lung cancer is recommended in specific populations. These recommendations exist because data shows they improve outcomes.

Blood tests like LDL cholesterol and ApoB are also strongly supported because they are linked to cardiovascular risk by extensive evidence and they are actionable.

In contrast, when a screening program is not grounded in strong evidence, especially in asymptomatic people, skepticism is warranted.

Focus on What Actually Moves the Needle

If your goal is better health and longer life, the biggest wins are not hidden in exotic tests. They come from proven levers:

• diet

• exercise

• sleep

• addressing major risk factors like blood pressure and cholesterol

Testing can help when it leads to clear action and improved outcomes. Testing becomes a problem when it creates anxiety, unnecessary procedures, and harm without benefit.

Sometimes, the best test really is no test.

Research sources:
https://www.bmj.com/content/355/bmj.i5745
https://www.nejm.org/doi/10.1056/NEJMc1507622
https://www.mja.com.au/journal/2024/220/1/first-do-no-harm-responding-incidental-imaging-findings
https://www.ajronline.org/doi/10.2214/AJR.22.28926
https://pubmed.ncbi.nlm.nih.gov/18954846/
https://www.acr.org/News-and-Publications/Media-Center/2023/ACR-Statement-on-Screening-Total-Body-MRI
https://jamanetwork.com/journals/jama/fullarticle/2680553
https://www.cancer.org/cancer/screening/american-cancer-society-guidelines-for-the-early-detection-of-cancer.html