Why & How to Use a Functional Medicine Approach to Lab Testing
By Erin Holt
If you’ve been looking for ways to help your clients in a more efficient and effective way, you might be considering incorporating a functional, root cause approach to your nutrition practice.
A functional approach can offer a way to provide more detail and help clients on a deeper level, but it can also be intimidating, especially if you’re not fully trained on lab testing yet or aren’t totally sure how or when to implement functional labs. You might even be hesitant to dive into functional lab testing because of the cost (I’ve heard it said before that “functional medicine isn’t very functional if no one can afford it.”).
Functional lab testing is certainly beneficial, but benefits only extend as far as your ability to read, interpret, and apply them to your practice.
The good news is that you don’t actually need functional lab testing to start taking a functional approach to your clients’ care.
Did you know that you can approach some very basic lab work—that doctors will run and is covered by insurance—through a functional lens?
First, it’s important to understand how the functional medicine interpretation of lab testing differs from the diagnostic testing done in conventional medicine.
The conventional healthcare model is very good at saying: you HAVE this and rarely asks the question, WHY do you have it? Functional medicine nutrition attempts to answer that question.
A key concept to understanding the difference between the two approaches is that the conventional approach is geared towards identifying pathology and disease. When running labs, reference ranges are looking for late stage disease development. At this point, in terms of treatment, the best we can really hope for is symptom management.
When we’re looking at health through a conventional lens, you either have a disease or you do not have a disease; if you do not have a disease, you are considered healthy.
The functional approach, in comparison, recognizes that illness doesn’t just pop out of thin air; there is a spectrum of health and the labs and reference ranges are trying to assess for early prediction.
We aim to identify imbalance of normal physiology so we can address these underlying dysfunctions and root causes— ideally before it gets to a pathological disease state. With this approach, we have the opportunity to restore balance and prevent or reverse the disease state.
Conventional lab reference ranges are based on a bell curve where 95% of people tested fall into a “clinically normal” reference range.
There are 2 chief problems with this:
If the average population in modern day is not the picture of health, then are we basing our “healthy ranges” on a sick population?
This is why we see so many people being told by their conventional health providers that their health is “normal” despite them having ongoing symptoms.
But just because someone does not have an identifiable, diagnosable disease, does NOT mean that they are healthy.
You can think about functional lab reference ranges as optimal ranges. We’re looking for a tighter, smaller range and anything outside of this tight range is considered suboptimal. It gives us clues that something within the physiology of that person is out of balance, EVEN IF they are not at a diagnosable disease state.
Let’s use blood sugar markers & Type 2 diabetes as an example.
Type 2 diabetes, insulin resistance, and metabolic syndrome is a complex web that creates vicious cycles—the more time it goes on, the more challenging it is to reverse. We can use functional ranges for basic blood work to stop this cycle in its tracks. However, if we’re using conventional reference ranges, we’re waiting until there’s a diagnosable disease state—at that point, it becomes a MUCH bigger problem to manage.
This is a great example of using a functional approach to lab testing without actually ordering a functional lab. This is a wonderful opportunity to use basic blood chemistry to our advantage. By using basic labs, but looking at them with a functional lens, we can catch things trending in the wrong direction early on.
Fasting serum glucose is part of a comprehensive metabolic panel and can give us some insight into our blood sugar levels.
Conventional lab reference range: 65-99
Functional/optimal range is 65/70-85
Keep in mind, I’m never *just* looking at these lab markers alone, but in relation to other markers, which is why I personally like to see fasting glucose, HbA1C and fasting insulin together. A functional approach when it comes to labs is pattern assessment: looking at lab markers TOGETHER within the overall context of the client, their story, and their symptoms. It becomes a problem—in both conventional medicine AND functional medicine—when we fall into literal translations of lab markers and get overly myopic of lab values instead of assessing overall patterns.
As I always say in the Funk’tional Nutrition Academy—we shouldn’t be treating the lab, we must treat the PERSON behind the lab!
Fasting glucose is telling us the blood sugar level at the time of the blood draw, so I also like to see that with HbA1C since it shows average blood glucose over the course of 2-3 months.
Prediabetes: 5.7 - 6.4
Diabetes: >6.4
Glycemic control for adults with diabetes: <7.0
Functional/optimal range is <5.4
With a conventional approach, many people with a HbA1C of 6.4 or under are being told their labs are normal. The process continues, and the next time you get blood work, the labs are higher. There is no intervention until you cross the lab reference range threshold.
However, with a functional approach, if we see numbers creeping up towards high, we recognize this is the time to intervene to make impactful change!
Fasting insulin is not one that is often measured, but should be because we can catch insulin resistance early on.
Conventional lab reference range: 2.6-24.9 (super wide range!)
By comparison, the functional/optimal range 3-8(ish)
Back in 2018 there was a paper published called. The Global Epidemic of the Metabolic Syndrome that referred to metabolic syndrome as “the new major health hazard of the modern world.”
Metabolic syndrome and insulin resistance affect the endocrine system, the immune system, and is a risk factor for chronic diseases of the liver, heart, and brain.
The cost of healthcare for metabolic syndrome (including rx meds, surgeries, hospital stays) is astronomical. In 2016 it reached $555 billion, and it’s expected to exceed $1 TRILLION by 2035.
Using functional reference ranges allows us to intervene on this metabolic process EARLY, so we can save healthcare costs AND LIVES.
I consider HbA1C, fasting glucose and fasting insulin to be foundational labs. Blood sugar dysregulation puts the brakes on all other health goals: hormone balance, energy, inflammation, thyroid, adrenals, weight loss, brain health and cognition, immune function, and autoimmunity. If labs are in suboptimal range, it is mission critical to help your clients balance their blood sugars. We outline many strategies—lifestyle, dietary and supplemental—in the Funk’tional Nutrition Academy.
Another example of viewing a basic lab through a functional lens is Vitamin D.
Vitamin D
Because vitamin D is critical to so many bodily functions, a functional approach considers optimal ranges to be higher than the standard conventional “sufficient” cut off. While the *exact* optimal range is debated, most functional providers agree that we want to see 25(OH)D levels at least 45.
25(OH)D
Clinical deficient: less than 20 ng/mL
Sufficient: 30 ng/mL
Optimal: 45+
Potentially harmful: 100+
If someone is low in vitamin D, the obvious reasons are lack of sufficient sun exposure and/or diet lacking in vitamin D-rich foods, which gives you the opportunity to work on diet and lifestyle changes with your client.
Beyond that, however, if someone is chronically low despite supplementation, this gives you the opportunity to do a deeper “root cause” dive into why.
Remember, a true functional approach isn’t just spot-treating labs—it’s attempting to understand WHY lab markers are imbalanced to begin with!
Potential Reasons for Low Vitamin D:
Not taking a high enough dose of vitamin D supplementation
Gut inflammation, infections, or dysbiosis
Magnesium deficiency (a necessary vitamin D cofactor)
Gallbladder removal
Poor fat digestion & absorption
Poor liver conversion
We do a deep dive on all these areas in the Funk’tional Nutrition Academy, but you can also learn with me for free with the Funk’tional Nutrition Podcast.
By leveraging basic, routine labs that can be performed by a primary care doc and looking at them with a functional lens, we can catch health imbalances BEFORE they get to the point of a disease state. It also gives us the opportunity to unpack the WHYs so we can take a more root cause approach with our clients.
This is the core pillar of the Funk’tional Nutrition Academy—teaching you not just how to get a better understanding of reading labs, but also how to peel back the layers behind lab markers and discover the unique triggers of the individual in front of you. To consider all the components—lab markers, symptoms and beyond—so you can meet your patients and clients more completely. THIS is a true root cause approach.
If you’re ready to help your clients on a deeper level, build lab skills & learn now to actually put all the pieces together in a protocol—FNA is the place for you.