Lab Testing Is NOT Reliable!

Published: October 26, 2012

Before the development of lab testing, most physicians had to rely on the art of medicine to diagnose and treat. They had to come to grips with their underlying insecurities and infallibility, and fall back on their art, mind, and intuition. This required listening to the patient as well as doing an examination. As technology evolved however, we have abdicated this responsibility to technology — resulting in great harm to our patients. We have turned technology into a sort of omniscient deity — putting all of our faith in it.

How many of us believe that something must be true if we see it in print? Do you take for granted what the newspaper tells you? If we do, I suspect we might be fools. If we believe that everything is fine because the blood tests are normal, then I suspect we are even bigger fools.

Most physicians were not taught what the "normal range" of testing actually meant during our training. Although nobody came right out and said it, we were given the strong presumption in medical school that the normal range was derived by scholars who pored over the scientific literature, determining what was healthy enough to allow us to safely presume that there was no problem. It therefore came as quite a shock to me when I looked up the national guidelines for laboratories to see how these normal ranges were derived. For a very large percentage of tests, the normal range is simply based on two standard deviations (e.g., out of 100 people, the highest and lowest 2.5% are defined as abnormal and the 95 in the middle make up the normal range)! Let's see how this works in real life using thyroid problems as an example.

The normal range for Free T4 thyroid hormone levels in the past have been based on the 2 standard deviations approach. That means if a problem affects over 2% of the population (as many as 24% of women over age 60 are hypothyroid and 12% of the population have abnormal antibodies attacking their thyroid), then our testing system will miss most of them. In addition, our testing system does not take biological individuality into account. To translate how poorly this "2% equals abnormal" system works, consider this: if we applied this approach to getting you a pair of shoes, any size between a 4 and 13 would be "medically normal." If a man was accidentally given a size 5 shoe or a woman a size 12, the doctor would say the shoe sizes they were given are "normal" and there is no problem! This is pretty close to an exact analogy of what happens when we overly rely on blood tests' normal ranges.

Unless your physician is willing to wear any size shoe in the normal range, it is not appropriate for them to refuse to help you because your tests are normal when your symptoms suggest a problem. Yet, this is more the rule than the exception (unless you have an open minded or a holistic physician — see Find a Health Practitioner).

What Happens When You Prescribe Based on the Patient and Not the Blood Tests?

In two studies done by Dr. G.R. Skinner and his associates in the United Kingdom, patients who were thought to have hypothyroidism (an under active thyroid), because of their symptoms (including pain), had their blood levels of thyroid hormone checked. The vast majority of subjects had technically normal thyroid blood tests. This data was published in the British Medical Journal. Since that time, Dr. Skinner has done another study in which the patients with normal blood tests who had symptoms of an under active thyroid — those who most physicians would likely say had a normal thyroid and would not need therapy — were given thyroid hormone. A remarkable thing happened — well, maybe it wasn't that surprising! The large majority of patients, despite being considered to have a normal thyroid, had their symptoms improve upon taking thyroid hormone (Synthroid®) at an average dosage of 100 to 120 micrograms a day. These two studies, plus another that indicated that thyroid blood tests are only low in about 3% of patients whose doctors sent in blood tests (and this is at an HMO where the doctor really suspected that the patient had thyroid problems), confirm what I have been saying all along. Our current thyroid testing will miss most patients with an under active thyroid. Once again, doctors of decades ago were on target when they knew that one has to prescribe based on the patient and not the blood test.

Although we use thyroid problems as an example here, the same principles apply to other tests. It is important that your physician pay attention to you, and not only your blood tests!

Jacob Teitelbaum, MD

is one of the world's leading integrative medical authorities on fibromyalgia and chronic fatigue. He is the lead author of eight research studies on their effective treatments, and has published numerous health & wellness books, including the bestseller on fibromyalgia From Fatigued to Fantastic! and The Fatigue and Fibromyalgia Solution. His newest book (June 10, 2024) is You Can Heal From Long COVID. Dr. Teitelbaum is one of the most frequently quoted fibromyalgia experts in the world and appears often as a guest on news and talk shows nationwide including Good Morning America, The Dr. Oz Show, Oprah & Friends, CNN, and Fox News Health.

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