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The Fallacy of the "Normal Reference Range"

What is "Normal" Anyway?

What Is Normal?
What Is Normal?



“Well, Mrs. Smith, I understand that your hair is all falling out, you can’t remember what you said to me 2 minutes ago, you’ve suddenly gained 20 pounds, and you can get out of bed in the morning, but there’s good news! We did some investigating, and your labs are back. They are all “normal”.”





Sound familiar? Yep, that’s right, everything is totally normal. Thank God! You thought something catastrophic had happened – I bet you’re thrilled to know that everything is just fine. Or, that it’s just in your head anyway. Is it?? Probably not. You’ve lived in that body for 50 years. Are you supposed to be led to believe by a lab result that you’re hallucinating the fact that the walls just caved in for no earthly reason? Perhaps you’ve just been hijacked by aliens or are in the middle of a terrible nightmare? Odds are, you’re not crazy. Well, you might be😊, but that’s not the problem here. The problem is our definition of the “normal reference range” for interpreting lab results. Let me explain: I have spent my entire career looking at labs. If the ‘normal reference range’ is so sacrosanct, why does every lab have a different one? I’m serious. Look for yourself. Dig out some old labs done by one facility and compare them to the same ones done by another. Perhaps the laws of physics are different at Quest than they are at LabCorp? Not the last time I checked. So how is it possible that a ‘normal’ TSH at hospital A is 0.4 to 4.50 but at hospital B it’s 0.33 to 5.0?


Here’s How: The normal reference range is a standard against which individual patient results are compared to a population of patient results. If the population around hospital A happens to be different than that around hospital B, so will be the reference ranges. This means the SAME lab result could be normal at one hospital and abnormal at another. That reference range determines how doctors make medical interventions, so it’s important. However, this unwavering reliance on these standard ranges presents a subtle, yet profound, fallacy in medical diagnostics.


The ’normal reference range’ is a statistical abstraction based on an average of lab values obtained – not by God, not by an all knowing medical edict determining optimal health – but by THE LAB. In most cases, it is the lab that determines the reference range. It does so by running a statistical analysis on the results of the labs they got from the people that went there. That’s it. They didn’t screen these people. These aren’t even likely healthy people. Who goes to the lab for fun? Labs are expensive! Is the lab soliciting wealthy biohackers with nothing else to do? Nope. Sick people have labs. Sick people are sent to the lab to get some objective data in an attempt to figure out why they’re sick. The lab then takes these results, adds them all together, and divides them by the total number they got. That gives us the ‘average’. A few strokes of the keyboard later and we have two standard deviations on either side of the average, and *voila*. There’s your “normal reference range”. This is often an incredibly broad range obtained from both healthy and unhealthy people. How is this meaningful? Well, that’s a good question and one that I spend a great deal of time discussing with patients every day. You don’t want your lab results to be compared against a reference range which includes your standard zombie walking around the grocery store. He clearly doesn’t feel well either, but I assure you, his lab results are included in that same reference range.

What we really want to know is an ‘optimal range’ when interpreting lab results. You didn’t need to pay for labs, then pay for a doctor visit to be told which side of the grass you’re on. Spoiler alert: You’re alive. To get to the bottom of why you asked the question in the first place, you want your lab results compared to those of people who have their shit together. You know, the healthy young ones with perfect hormone levels, perfect insulin control, perfect adrenal function, and zero unnecessary inflammation. Where’s that reference range? Well, most often it’s hidden somewhere inside the standard reference range. Sometimes it’s at the lower end, sometimes it’s at the upper end, and sometimes it’s a tight range, right smack dab in the middle.

So, what does this mean for you, the patient who is earnestly seeking answers to unexplained health questions? It means that it’s time to demand a deeper, more personalized interpretation of your lab results. A “normal” lab value does not always translate to optimal health. In fact, it rarely does. It just means you’re alive. Normal results are often a statistical mirage lost in the murky averages of the sick majority of everyone else. You want “optimal” lab results. Personally, I don’t want my results compared to just anybody – I want mine compared to the healthiest people.

A crucial aspect that is often neglected is simply individual variance. What’s normal for one person isn’t necessarily normal for another. The ‘one-size-fits-all’ approach is the exact opposite of personalized medicine. Our genetic makeup, lifestyle, dietary habits, and environmental exposures contribute to our distinct biochemical individuality. Thus, our lab results should be interpreted within the context of our unique health status, history, and symptoms, rather than just compared against a generic ‘normal’ standard.

OK – easy enough to say, but how are we to navigate through this? First, it’s critical to find a healthcare provider who understands this nuanced perspective. A provider who is willing to treat you as an individual and not just another statistic in a database. They should be able to discern between what’s statistically ‘normal’ and what’s clinically relevant and optimal for you. Furthermore, educating yourself is imperative. Be an advocate for your own health. Ask questions, seek clarifications, and don’t hesitate to discuss the implications of your lab results thoroughly with your healthcare provider. If he or she can’t or isn’t willing to have that discussion, you need to find a different doctor. Remember, you are not merely a passive recipient of healthcare services but an active participant in your healthcare journey.

In conclusion, while reference ranges can serve as a guiding tool, they shouldn’t be the end-all/be-all in medical diagnostics and patient care. A holistic, individualized approach that incorporates the entirety of a patient’s health picture is indispensable for achieving truly meaningful and actionable insights from lab results. No one wants to be just existing; you want to be optimized. The fallacy of the normal reference range underscores the need for a paradigm shift towards a more nuanced, patient-centered approach in interpreting and utilizing lab data for optimal healthcare outcomes.

If you feel like crap, I bet through the lens of an optimal range, your labs look like crap too. You deserve to understand why. Then we fix it.

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