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What do you mean my labs are normal?

What do you mean my labs are normal?I couldn’t even …

What do you mean my labs are normal?

I couldn’t even begin to say how many times I come across this issue in a week – sometimes in a day. Someone comes into my office; I read social media; or even talk to a random person somewhere, and they say to me “I feel awful, but my doctor said that my labs are normal.”
How could all of my labs be “normal”, if I feel awful?

Meme borrowed from the Interwebs. Original source unknown. All credit due to original owner.

Let’s explore “normal” – or in this case, what information is being used to determine a normal lab range. First and foremost, it’s important to acknowledge that lab ranges are based purely on statistics – nothing more and nothing less. Let me elaborate.

Let’s say that we take a sample of 100 people. Out of those 100 blood samples we’ll get a “standard normal distribution”. (Bear with me here, I know stats gives us all the twitches, but it’ll make sense in a second). There will be a mean (middle value) in the middle of the Bell curve  – and things will shake out roughly evenly on both sides – with 95% of the lab values (or in this case, 95 samples) being in the main part of the curve, and 2.5% on each side of that.

bell curve95 sm

With me so far? Ok. Now. Knowing that this is based on samples and sample sizes, do you think that it matters where the samples come from, how many samples were used,  what type of population the samples come from, or how healthy the samples are, etc etc etc?

 You better believe that it matters.

To add an element of complication, there are no standard ranges. Each laboratory can determine their own “normal”. There is no universal standard. There are no qualifications (with very few exceptions) for genetic sex, race, age, geography, diet, etc. And remember, those lab ranges are based on the population sampled – NOT necessarily YOUR population, and not necessarily based on healthy function. The assumption made is that if there is a sample size, that if enough people fall within that sample range, that must be normal function.

Here are two examples that I sometimes use to illustrate this:

Back in 1986, the nuclear power plant at Chernobyl exploded. What if we had sampled 100 people, affected by that explosion, for radiation exposure – to establish a distribution of “normal” blood levels of radiation? We might get a bell curve of values, but if we determined that “normal function” was based on the values that we received, that would be far from the truth – as those folks would have FAR more radiation exposure than say, some folks living in rural Iowa – thousands of miles away from any kind of nuclear anything. Would we use their lab values within 95% to be considered normal? Nope. But it would be a normal distribution for that specific population. Would we consider those to be normal/health/optimal function for radiation exposure? Not a chance! That’s kind of a crazy example – but here’s a real one.

Since the early 1990’s, the “normal distribution” for Vitamin D levels has changed significantly. I can personally account that I have watched the low “normal” range drop from 40 nmol/L to 20 nmol/L – depending on which lab company is being used. This is based solely on statistics. The individuals included, within the sample for range determination, made the lower end of the 95% cut off move all the way down to 20. Some labs will go on to separate those values into insufficient, sufficient, optimal, excessive, or whatever – but most labs simply report a low out range value and a high range value.

Now, how does this happen?

For one reason or another (poor diet, indoor exposure, sunscreen, etc.) that low range value; i.e. the lowest number reported within the 95% of samples – has dropped by 20 nmol/L in the last 30 years. Did we figure out that the low-end value of required vitamin D changed? No. Not at all. In. fact, research – depending on the population, age, and any extenuating health condition – seems to indicate that optimal, functional vitamin D levels START around 60 nmol/L.

This is why it’s so absolutely crucial to evaluate lab levels by function, and not statistics. And just another explanation for why labs might come back “within range” and you might still, not at all, be healthy.

You might want to go take your vitamin D. You’re probably deficient.*

*Testing recommended

Light Reference Reading:

https://pmc.ncbi.nlm.nih.gov/articles/PMC3739683/

https://www.merckmanuals.com/professional/resources/normal-laboratory-values/normal-laboratory-values

https://ascls.org/wp-content/uploads/2012/11/Brochure_Laboratory_Reference_Intervals_Providers_2019.pdf

https://www.pathologyoutlines.com/topic/labadminreferenceintervals.html

https://pmc.ncbi.nlm.nih.gov/articles/PMC2556592/

https://pmc.ncbi.nlm.nih.gov/articles/PMC4494470/

https://pmc.ncbi.nlm.nih.gov/articles/PMC2665033/

https://pmc.ncbi.nlm.nih.gov/articles/PMC8224373/

drandrealotken

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