Wednesday, September 10, 2014

The Reference Range Fallacy




Medical science has finally found a solution to the obesity problem in the U S. And, incidentally, the high cholesterol problem can be solved in exactly the same way; by applying the same standards and logic that are applied to so many other health factors; the reference range.

How would that help, you ask? Well, the standard reference range is set so that the middle 95% of those tested are withing range with 2.5% being below range and 2.5% being above range. The assumption is that 95% of the population is normal...or healthy...or at least ok.

The data available shows that the upper, or out of range, 2.5% in BMI is somewhere above 40. The lower, I would conjecture, is somewhere around 10. So the “expected” BMI range would fall between 10-45 or so. If doctors treated BMI the same way as they do so many other conditions, then there would be no problem for so many; they'd all be in range! Incidentally, a total cholesterol of 270 puts a person in the 95% range, so you can still increase your cholesterol, at that level, and be within range.

As an aside here, I would guess that the bottom 2.5% total cholesterol number would be around 75. Cardiologists would love this! Because if you could get your total cholesterol that low you would never suffer a heart attack/cardiac event! The heart docs would be high fiving and bragging about how well their treatments work. No cardiac events, you ask? That's right, because with total cholesterol that low you'd commit suicide or die from other maladies before the heart would have a chance to act up!

Of course, I'm not serious about using reference ranges with things like cholesterol and obesity. That would be silly and illogical. But then, why do doctors insist on using reference ranges in so many other areas that are just as silly?

Granted, there are some things for which doctors routinely check regardless of symptoms. For many of these, especially when the numbers tested are high enough to represent the general population, the 95% “ok” assumption might be valid. But for so many things, testing is only done when symptoms of a particular condition present. And for many of those conditions, the reference range is lab specific, not even adding in data from other labs. To assume that 95-97.5% of those exhibiting symptoms are really “ok” is rather a leap of faith.

As an example, let us look at what might be a typical lab associated with an endocrinology clinic. And let us look at the testosterone reference range. For a particular lab, the range is somewhere in the area of 175-750. Most labs give a low end number of between 250-350. Some labs even have a low end in the 400's. Why would this lab be so different?

Well, first ask yourself who gets tested for testosterone levels. I guarantee you, it's not the guy with no problems, whose parts are functioning well, and who has a happy and frequent sex life. So even the guys being tested by their family doctor are ones who have exhibited symptoms of low testosterone. Now who goes to the endocrinologist? That would be those worst case folks whose symptoms the family doctor hasn't been able to alleviate!



And we are going to assume that 97.5% of those being seen by an endocrinologist for symptoms of low testosterone are really ok because they are within the clinic's lab generated reference range? I have a really hard time accepting that! But many doctors take it as gospel! Never mind that studies show levels above 550 decrease cardiac events by 30%. Either the doctors haven't bothered to keep up to date on the latest studies, they don't believe the studies because it wasn't what they were taught, or they just refuse to change their methods.

Reference ranges say nothing about health, wellness, or functionality. They simply give an indication of the relative status of those being tested. In the land of the leper, the leper is normal!
I prefer to be healthy rather than normal!