So you went to the doctor, you thought you had something wrong and everything came back normal, but you still really feel sick. Let’s talk about the meaning of normal laboratory ranges. First of all, I just want to make something clear, the idea behind my articles is not to diagnose yourself or others, but to educate by explaining complex medical principals in layman’s term. My hope is that you’ll get better at judging the validity of the information read in newspapers or covered in different popular TV shows and that you get a better understanding of your own physiology to either explain your symptoms in a more accurate way to your health practitioner or to be better at asking questions to them. That being said, today I’ll explain what is a normal value.
So you are a big medical company. You sell laboratory equipment like those big machine you put blood in to measure the number of red blood cells, white blood cells and so on. For your own education we call that the haematology department (I must confess, I really like etymology as it helps so much to understand complicated words so if you want to know…heamato means “blood”, logy means “branch of learning” so it’s basically the study of blood cells). Getting back to the example, so you have this machine, you did your research, your tests with standardized solution to make sure that it’s accurate (with slight variation). Now you want to set your normal range. What you do is you take few thousand “healthy” individuals (without any major illnesses) and measured their level of red blood cells (RBC) in the blood. You put them all on a chart that will look like the second image above.
So the majority of the population you measured will be concentrated in one particular zone and spread on each side. Statistically, what you do next is that you take the 2,5% on the left and the 2,5% on the right and call them outside the range. There you go you have your normal range, your 95% of your population. But what if you live in a different part of the country or in another country, different population? Yes exactly, different normal ranges. So you may be normal if you test yourself where you live, but take the next train for another lab, test again and you may now be outside the normal range! Who should we trust right? Well, although some test like hormonal level could have a decent difference, usually the difference is not high.
Next question, what define a healthy population? Well it’s easy right? Someone who is not sick… I’m pretty sure you know enough people around that don’t have the same lifestyle, although not sick, that are not up to par health wise, but still you are compared to them do define your normality.
In functional medicine, a word used on top of normal range is optimal range. Let me explain this one. Ok from a big medical company owner, you are now a teacher. You teach in a driving school. You ask your students to do an exam only on road signs. Because of your experience in statistics, you decide to do a bell chart from their results. So let’s say the range is from 50% to 100%, your 2,5% bottom range is 56% and top range is above 94%. Technically, your normal range would be 56 to 94. Lower than that, the student is too low and above…well too good, maybe he cheated..just kidding, but you get the point.
Now would you say that a person who can read only 56% of the road signs properly (knowing that 5 times out of 10 he is wrong) will be as safe as the one who can read 94% (all other factors excluded of course)? They are both in the normal range but one will misinterpret half of the signs. So we decide that there will be an optimal range so top 1/3 of the normal range. So maybe 80% to 94% will be our real target. This example ranging from 56 to 94% sounds a bit silly right? What if I tell you that some labs use a testosterone range for male of 348-1197 ng/dL? You think that the one at 348 and the one at 1197 feel exactly the same? But they got their results and they are both normal… Maybe one of them as low libido, I wouldn’t be surprised.
On top of that, keep in mind that the blood test results you got are only a picture of what’s going on, it’s the level you had at that exact moment the nurse has drawn your blow. It doesn’t mean it stays at that level all the time. For example, a big training session can increase the CK (creatine kinase) to double the normal value the next morning, so basing the diagnostic just on the value of the CK without having the whole story being it, one could think you’re having an issue with your CK which could mean degradation of the muscles, heart attack or even brain trauma! To reassure you, if CK is too high, by law, it is mandatory to measure the CK fractions (CK-MM, CK-MB, CK-BB) to know where the CK comes from (in order, muscle, heart, brain).
Knowing what a normal range means is really important. It is not just above or beyond the laboratory set ranges. You now understand that being “normal” means only that when compared to the average population, your numbers are not in the top or bottom 2,5%. You need the whole story behind the numbers, the symptoms, compare past and actual results.