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Paul Spector, M.D.

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Normal Medical Lab Results Not So Normal

Posted: 04/17/2012 10:13 am

These days, the typical annual check-up is inevitably preceded by "blood work." The technician assembles what appears to be enough tubes to drain your tank. (After seeing the little tubes used for babies and young children, I've wondered why adults can't do the same.) You watch the deep crimson liquid flow into the test tubes and hope it harbors no surprises, that everything will be analyzed and found "normal."

In our medical system, health is defined in the negative, the absence of abnormal findings. Medical language reflects this in the curious nomenclature of test results. A "negative" test result means you're not sick, a positive thing. The medical field continues to define health as the absence of disease, an impoverished conceptualization that underlies the most fundamental problems in our health care (it should be called sick care) system.

Over the past 20 years, the history-taking (a time when physicians sat with patients and got to know them, who they lived with, the work they did, the family story, the struggles, their habits, their vices and values, in other words got to know what was "normal" for them) and physical exams have been eclipsed by sophisticated blood tests and imaging techniques. This is a casualty of dramatic advances in science and technology as well as financial pressures that encourage abbreviated visits and greater patient volume.

So you might have a quick chat before undressing for a rapid physical exam. When you rejoin your doctor at her desk, she takes a moment and pages through your chart. She scans the lab results checking the abnormal column. If it's clear, you're good to go. "See you next year. You're fine."

But where do these normal ranges come from? A reasonable person might presume normal ranges are defined by the test results of people whose health has been carefully scrutinized and found to be optimal.

Wrong.

Normal lab numbers are determined by huge reference laboratories. Let's take blood glucose as an example. All the glucose test results from the past few months are pooled. The middle 95 percent is defined as "normal." If you fall in the 2.5 percent above or below that range, you have an abnormal blood glucose. In other words, the medical use of the term "normal," which is understood to mean healthy, is really a statistical concept.

There is an attempt at refining the normal ranges by using information about age, gender, and location. So a 70-year-old male in Flagstaff, Ariz. will be compared to more men around that age than anything else. But no diagnostic history is available to the reference labs. Test results from venues that are thought to have mostly "healthy" people, such as health fairs, are also used. But isn't someone more likely to get blood drawn at a health fair if they think there might be a problem?

So let's take a look at how this plays out. Your annual blood glucose creeps up each year, but remains in the normal range for a decade. Year 11, your doctor says, "Bill, I'm afraid you've got a sugar problem." Bill thinks, "Wow, and last year I was fine."

Bill was not fine.

So there are three fundamental problems. One, we are compared to a population, many of whom are not healthy. Two, 99 percent of physicians do not follow trends in your lab values in order to catch a problem before it's progressed to a point where it compromises your health. And three, most physicians no longer "know" their patients.

Mant of the most common illnesses of our culture are chronic, such as diabetes, coronary artery disease, high blood pressure, and obesity. The kind of medicine I've described above is partly to blame. You don't wake up one day with a chronic disease that you didn't have the day before. Nobody became obese or diabetic or hypertensive on Tuesday. Until preventive medicine replaces the acute care model, it won't get better.

What You Can Do:

1. You are the most important member of your health care team.

Own a copy of your test results. The system is broken and you can not assume essential data will be available to the doctors making decisions about your care. It is your job to make yourself "known" to your doctor. You must inform her of what "normal" (as defined above in history-taking) life is for you.

2. You provide your own normal lab reference range. Get a baseline set of blood work when you're well in order to keep track of your results over time.

Address trends early and do not wait until results have hit the abnormal range.

3. Take all medical statements about your health with a dose of skepticism. The doctors can provide information about large populations. That is not the same as knowing what is necessarily in store for you.

Do your homework. Read about your condition. Get second opinions.

For more by Paul Spector, M.D., click here.

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