Average is Not Optimal- Why Functional Medicine Test Marker Ranges Differ from Conventional Medicine

November 9, 2022

What Is The Purpose of Disease Diagnosis?

We answered this question in a past article of ours on diabetes diagnosis [1]. Quoting from the article:

“When a specific blood marker(or any other test) exceeds a specific cut-off, we assign an official disease diagnosis. This is because when the diagnostic criteria for a disease are fulfilled, it means the patient is at risk for experiencing certain known symptoms or is already experiencing them and it is happening due to a certain known condition which is supposed to be the disease. Hence, the best diagnostic test is one that is best able to predict and correlate with symptoms. That is the purpose of medicine.”

So how well has medicine been serving its purpose in the conventional system? 

Have you or anyone else you know suffered from debilitating chronic health issues only to be informed by your doctor that all your tests look normal and there is nothing wrong? This is increasingly common today.

1. “It’s all in your head”

The next step usually is one of subtle gaslighting. In the absence of physical issues, the symptoms are deemed psychosomatic and you’re referred to a psychiatrist who will then prescribe antidepressants. Often physicians will hand out these psych drug prescriptions themselves. Almost half of antidepressant prescriptions handed out each year are for conditions other than depression, a study published in JAMA found [2].

“In my practice and experience, we have found that antidepressants help with a lot of conditions including irritable bowel syndrome, bulimia, and even anxiety,” says Niket Sonpal, M.D., assistant clinical professor at Touro College of Medicine in New York City [3].

The use of antidepressants for a variety of issues makes sense in some ways, says Dr. Sonpal. 

“The mind-body connection is] so much stronger than we estimate and frankly even understand,” he says. “There is interplay of our brain, mood, and disposition with the rest of our body”.

Dr. Sonpal is right about that. Knowing what we know about the mind-body connection and the gut-brain axis, it’s easy to see why psychological drugs might help with physical conditions. 

But “helping” isn’t curing. The use of antidepressants in this way might serve the conventional medical system well, that for most chronic disease conditions, only just helps to manage the symptoms of the disease only. But functional medicine believes in extensive testing and analysis to uncover the root causes of diseases and reversing them for a permanent cure.

2. Names for the unknown: “It’s not in your head. We have a name for it in our textbook now”

The number of cases of chronic disease conditions that conventional medicine is unable to explain was probably getting a little too high. This, perhaps is the reason behind the emergence, in the last couple of decades, of many new diagnostic labels based purely on symptoms only. With no causative mechanisms identified.

It’s always been a characteristic of conventional allopathic medicine to assign more and more disease labels to chronic health dysfunctions. This has only increased recently with many “syndrome”-type disease diagnoses which are basically nothing but a collection of commonly associated symptoms for which there is no officially recognized cause. Treatment often involves trial and error with a fixed set of drugs allocated for the condition.

From the article, ‘Disease, Diagnosis or Syndrome?’ in BMJ Journals, 2011 [4]:

“Medical terminology of diseases, diagnoses and syndromes is inherently imprecise. Careless nomenclature causes confused dialogue and communication. Symptoms of uncertain cause are commonly lumped together and given a new ‘diagnostic’ label which also may confuse and produce false concepts that stultify further thought and research. Such medicalisation of non-specific aggregations of symptoms should be avoided. The defining characteristics of diseases and diagnoses should be validated and agreed. The pragmatic diagnoses of ‘symptom of unknown cause’ or ‘non-disease’ are preferable to falsely labelling patients with obscure or non-existent diseases.”

This approach of the conventional system to use so many diagnostic labels might seem ironic given that they actually use fewer diagnostic tests. It’s in stark contrast to the approach of functional medicine- more testing, fewer labels. Functional medicine runs many times more tests on clients and does not have any extensive system for labeling diseases.

But if you think about it’s not ironic and actually makes sense- since, in functional medicine, there is such a high amount of data on each client including many different variables and markers, it becomes more difficult to push every case into pre-defined disease boxes the way that conventional medicine does. The functional approach is highly bio-individualized- we recognize that each case is complex and unique. Symptoms and test data usually reveal the presence of multiple health conditions to varying degrees. More extensive testing helps us identify the root causes instead of the downstream effects the patient experiences as symptoms. This is how functional medicine is able to permanently reverse complex chronic conditions.

 A lot of the nomenclature that functional medicine(and other holistic practices such as integrative medicine) does utilise- such as Leaky Gut, SIBO(small intestine bacterial overgrowth), and Adrenal Fatigue revolves around causative agents rather than symptom presentation. Conventional medicine refuses to recognize any of the aforementioned terms. 

3. “We’ll suppress it with drugs”

Conventional medicine misses out on problems occurring in the body because their testing is inadequate and data analysis is not properly formulated. We go into the details of this later, but it is important to note that even when they do get it right and provide an accurate diagnosis, it’s in no way a home run. But far from it. Because it still does very little to help the patient. Because as we mentioned above, the conventional treatment for chronic disease conditions only involves suppressing symptoms with drugs. Statins to lower high cholesterol, metformin to reduce high blood sugar, antacids and PPIs to control acid reflux, steroids to suppress autoimmune conditions, sedatives to control anxiety, antidepressants for depression- the list is endless.

So Why Do The Assessment Ranges for Tests Differ Between Conventional And Functional Medicine?

The conventional system is surprisingly unscientific when it comes to this aspect of medicine. We know it’s common for the scientific process to often be corrupted and not properly adhered to in mainstream medicine. But the reason we say” surprisingly unscientific” here is because there isn’t even an imperative to follow the scientific method here. The standard practice for assigning assessment ranges for tests in conventional medicine is by formulating an average value from the collected test data in diagnostic laboratories. So the assessment range we see is the peak of the bell curve that forms upon plotting the frequencies of result values across the entire range [18][19][20][21][22].

What they’re basically assuming is that the average value is the optimal value. Which is obviously a flawed approach. Consider, for example, if you take a certain group of people and expose them to a particular known health stressor, say a low dose of mercury(a toxic heavy metal). Some people in the group would start to exhibit symptoms. When you test mercury exposure levels in the group it would be high on average. Now, to say that this high level is okay because everyone in the group has these high levels is obviously incorrect.  

The above isn’t a hypothetical example: the Minamata disease(originating in Minamata Bay in Japan) in the 1900s in Japan saw thousands among the fish-eating coastal population in Japan suffer from neurological impairments due to mercury poisoning through the industrial wastewater from a chemical plant. Mercury toxicity is now a global problem. The WHO estimates that among fishing populations of the world, mercury poisoning might affect as high as 1.7 percent of children [17].

Similarly, in mostly vegetarian populations in developing countries like India, we find very low B12 levels. Again, that does not mean the low levels are adequate.

Average of a Sick Population

In our modern urban lives today, we are all exposed to a vast amount of health stressors-toxins in our air, water, and food, EMF radiation, and our stressful modern daily routines, just to name a few. All of this has been a rapid development only in the last 10,000 years or so. Compared to the 2.5 million years before that when we followed our hunter-gatherer lifestyles. We haven’t evolved to adapt to all of these health stressors and they affect all of us adversely to different degrees and are responsible for almost all modern-day chronic diseases we see today. Because of this, the statistical population average of most of our health markers is far from optimal. 

You might think that functional medicine has an impractical model because in today’s environment, perfectly optimal health markers are not possible. 

We do understand that it’s not possible. And we don’t necessarily aim to get every single marker within the optimal range for every individual. But to say that sub-optimal ranges are all okay and that there are no physiological issues with an individual presenting with sub-optimal health markers(which is what conventional medicine does) is a problem. This is exactly why and how so many individuals suffering from chronic health issues have all their tests come back as normal. 

The reason conventional medicine allows for sub-optimal ranges to pass as okay is because having sub-optimal markers do not cause major noticeable issues in the majority of the population. It’s only a small minority, the canaries in the coal mine, who suffer. 

Health stressors affect different people to different degrees, causing noticeable problems only in a few. The functional medicine approach to treat these cases is by trying to undo the effect of health stressors on the body as far as possible, in order to alleviate disease, and or improve the person’s health. Our bodies have an amazing ability to heal themselves- when the underlying chronic health stressors are removed, the failing organs heal back. Often support in the form of nutrient therapy or herbs and supplements is required. This is what functional medicine aims to do. What we see as chronic disease symptoms are most often the end result of a long-term domino effect that begins with health stressors. 

As mentioned, we don’t necessarily aim to get every single marker within the optimal range for each individual but the more advanced optimal assessment ranges along with the larger number of markers help identify root causes or dysfunctions in the body at an upstream causative level.

With recent advances in medical science in the field of epigenetics and gut microbiome, we can actually identify exactly what it is that causes some individuals to have adverse reactions to particular health stressors but not others and initiate treatment to make changes to the same.

Healthcare vs Sick-Care

Even in individuals who may not be exhibiting any symptoms, sub-optimal markers are indicative of a high risk of future diseases. Thus warranting preventive healthcare interventions. Instead of telling the patient that everything is normal and there is nothing to worry about. 

This is the reason functional medicine markers tend to be narrower. Conventional medicine waits till the condition has progressed far enough to be diagnosed as a disease state.

“Functional ranges define the parameters of good health while lab ranges define the parameters of disease.”[18]

It gets worse

So, the fundamental point of difference between conventional and functional ranges is that the former is derived by taking the plain statistical average of all results available at diagnostic laboratories- the peak of the bell curve, as we mentioned earlier. While our current modern society as a whole is quite unhealthy and far from optimal, what makes matters much worse is that the people who do go to labs and get tested are most often people who are sick. Ones suffering from one or more issues which is why they’re getting tested. So the average value we see is not even the true average of the entire population, but actually from the more sick section of the population! 

Lab ranges also vary from region to region in most countries. All of this just goes to show how unscientific the entire process is.

Functional medicine ranges, which are the optimal ranges, on the other hand, are obtained by extensive research with the test markers to find out what values correspond with the best health outcomes and what values correspond with increased incidence of any health problems or mortality.

The above approach is adopted to an extent by conventional medicine as well, for a few test markers of notable importance such as blood sugar and cholesterol levels. But even so, they still tend to be biased toward the average value instead of what the research really shows as optimal.

To demonstrate what we are talking about we will now go through 3 examples of blood tests whose assessment ranges differ in functional and conventional medicine, and attempt to analyze why the differences occur.

1. Fasting Glucose

Conventional range:65(or 70)-99 mg/dL,  100-125 mg/dL is “pre-diabetic” and >125 is diabetic

Functional range: 82-88 mg/dL

Fasting glucose is often used in isolation by conventional doctors to diagnose diabetes. We don’t think this single marker is significant enough to base the entire diagnosis upon. For testing an individual’s blood sugar management ability, we think tracking blood sugar over an extended period of time using a continuous glucose monitor or repetitive blood sugar testing is most effective. Other markers like HbA1C are better options as well. For metabolic health in general, serum insulin, triglycerides, HDL-to-LDL and HDL-to-triglycerides are good markers.

Fasting glucose, by itself, though can be helpful in predicting certain health issues like insulin resistance and cortisol dysfunction. Based on all the current literature, the upper range of 99 followed by conventional medicine is too high. There are many studies showing that a higher fasting glucose, within the current conventional upper range of 99, is associated with significantly higher rates of cardiac issues and diabetes onset [6] [7] [8] [9] [10] [11].

We do see some acknowledgment of the above-cited research in the mainstream literature and there is some hope that the upper range may be lowered to 90 mg/dL in the future, especially considering the urgent need to address the skyrocketing rates of metabolic disease prevalence globally today. 

From an editorial article titled “Doctor, Is My Sugar Normal?” in the New England Journal of Medicine in 2005:

“Fasting plasma glucose levels in the high-normal range (91 to 99 mg per deciliter) in young men and women warrant counseling with regard to weight and lifestyle, as well as an assessment of the lipid profile. Markers of future disease are always very useful when prevention is possible. There is ample evidence that this situation is true in the case of diabetes. “Yes, your glucose level is normal, but let's do something about that weight and your sedentary lifestyle” is too frequently the most appropriate response to the question, “Doctor, is my sugar normal?” [12]

It used to be worse before, until 1998, when the conventional upper range(for diabetes diagnosis) was brought down from 140 mg/dL to 125 mg/dL by the American Diabetes Association. 

While there isn’t much research on the lower threshold, we find the current value of 70 to be too low. This is based on our clinical practice where we often find patients suffering from hypoglycemia symptoms like anxiety, tremors, brain fog, palpitations, dizziness, etc in patients with fasting glucose in their 70s. Once fasting glucose is brought up to the 80s through nutritional interventions, symptoms disappear.

A study which analyzed medical data from 40,069 people found that individuals with fasting glucose below 70 mg/dL had a 3.3 times higher risk of death from cardiovascular disease and those with fasting glucose in the range 70-79 mg/dL had a 2.4v times higher risk.[5]

High Fasting Blood Sugar Can Be Healthy: Context Matters

The example of the fasting glucose marker is also a good one to demonstrate why the kind of bio-individualized approach that functional medicine follows that takes into consideration the person’s diet and lifestyle is important. Fasting glucose is typically much higher for individuals who are adapted to a low-carb-high-fat eating pattern. This is because their metabolic system is uniquely adapted to using fat for fuel instead of sugar which results in their fasting glucose levels being elevated naturally without it being pathogenic [5]. This is important to consider as low-carbohydrate and ketogenic diets are extremely popular worldwide today with more and more people adopting them as a lifestyle. The conventional system does not take into consideration people’s diet and lifestyle and can thus blankly label a healthy individual on a low-carb diet as being sick with diabetes this way. 

2. Uric acid

Conventional range

Men: 4.2-7.3 mg/dL    Women: 3.2-6.1 mg/dL

Functional range

Men: 3.7-5.5 mg/dL   Women: 3.2-4.4 mg/dL

The upper ranges for uric acid are too high in the conventional system. Studies clearly demonstrate that a high uric acid value within the current conventional range is associated with significantly higher rates of heart disease [13] [14] [15] [16].

3. Thyroid

The thyroid panel is a good example to demonstrate how extra tests in functional medicine help us identify root causes of chronic conditions to help permanently reverse them.

The thyroid gland and its associated hormones make a very complex sophisticated system. This is why it is very difficult to treat thyroid dysfunction. There are a number of different things that could go wrong and for an even larger number of reasons why. This is why it is difficult to uncover the root cause of thyroid dysfunction even for holistic practitioners. 

The conventional treatment, as usual, is symptom suppression- replacement hormones are used, usually synthetic. This does not work long-term and their effect wanes with time. Because the underlying cause is left untreated. The underlying cause in most cases is an autoimmune condition called Hashimoto's disease where the body is chronically producing antibodies that attack the thyroid gland and damage it. Ninety percent of hypothyroidism cases are caused by this autoimmune condition. 

Conventional treatment for autoimmune conditions is to suppress the immune response with steroids. But in this particular autoimmune condition, no effective immune-suppressive treatment has been found. So early or intermediate-stage Hashimoto’s is simply left untreated until the thyroid dysfunction progresses enough to be recognized on a clinical level as hypothyroidism. Then the standard treatment with replacement hormones is initiated.

Apart from Hashimoto's other common causes of hypothyroidism are:

Pituitary gland dysfunction:  Incorrect signaling from the pituitary gland to the thyroid gland causes the thyroid gland to malfunction even though there is nothing wrong with the thyroid gland itself.

T4 to T3 conversion hindrance: T4, the inactive form of the thyroid hormone, must be converted to active form T3, which happens in the cell membrane. Due to inflammation, the cell membranes often get damaged which in turn hinders this conversion.

TBG levels dysregulation: Thyroid Binding Globulin or TBG is the protein that binds and transports thyroid hormones in the blood. Abnormal TBG levels can cause hypothyroidism. Issues with abnormal levels of TBG can be detected by testing free T3 and free T4(unbound forms of the thyroid hormones) and also by testing T3(because T3 levels fall). 

Thyroid resistance:  In this situation, both the thyroid and pituitary glands are functioning normally, but the hormones aren’t getting into the cells where they’re needed. This causes hypothyroid symptoms.

Note that all lab test markers will be normal in this pattern because we don’t have a way

to test the function of cellular receptors directly. Thus this condition is suspected when all markers appear to be optimal.

Conventional medicine does not recognize or test for any of the above causes. It has a one-size-fits-all protocol for all cases of hypothyroidism- hormone replacement therapy.

The conventional system only tests for TSH and T4 in their thyroid panel. Key parameters T3, free T3, free T4, and thyroid antibody testing(to identify Hashimoto’s) are all left out.

And even in these two markers used, the lab average ranges are considered which are much wider than optimal ranges. This is why official diagnosis only happens at a much-advanced stage of hypothyroidism only.

Why Diagnose Less If You Wish To Make More Money?

Before we wrap up, we wish to address an obvious question that we think may arise in the minds of some of our readers. We accuse the conventional medicine system of being corrupted by Big Pharma to maximize the latter’s profits. Why then would they choose to diagnose lesser people instead of more with any particular disease when doing so reduces the number of people they can sell their treatments to? This is a good question since there does not appear to be a clear answer. While there are many cases that demonstrate that conventional medicine does definitely try to incentivize drug sales- such as maintaining the idea that serum LDL Cholesterol is a risk factor for heart disease and lowering the acceptable range to sell statin drugs. Even the lowering of the fasting blood sugar levels for diabetes diagnosis that we talked about earlier, though a positive development, has often been accused of as being a move to sell more diabetes treatments. Unwarranted diagnosis and treatment with psych drugs is rampant for mental health conditions today, The diagnostic criteria for clinical depression were drastically loosened in the last edition of the DSM. Both statin drugs and antidepressants are each large industries by themselves today.

Despite cases such as the ones mentioned above, diagnostic ranges in conventional medicine continue to be much wider than in functional medicine. Some accuse the conventional system of deliberately letting people progress to a fully diseased state in order to make permanent customers out of them-a very diabolical accusation to make.

We think it’s important to also consider here how the conventional system differs right at its inception stage(before and if any corruption could play out). The conventional system is the basic standard of medical care that aims to provide rudimentary medical coverage for the entire population. It only aims to prevent deaths and keep people alive and away from serious diseases. Functional medicine, in contrast, is a specialized premium healthcare model that focuses on wellness and helps get people to their best possible health. The detailed health analysis it uses is able to help heal people suffering from complex hard-to-treat chronic conditions.


[1] https://www.ithrivein.com/blog/testing-for-diabetes-what-are-the-most-reliable-markers

[2] https://jamanetwork.com/journals/jama/fullarticle/2524175

[3] https://www.menshealth.com/health/a19521614/doctors-prescribe-antidepressants-depression/

[4] https://pn.bmj.com/content/11/2/91

[5] https://high-fat-nutrition.blogspot.com/2007/10/physiological-insulin-resistance.html

[6] https://pubmed.ncbi.nlm.nih.gov/21492487/

[7] https://pubmed.ncbi.nlm.nih.gov/18501234/

[8] https://pubmed.ncbi.nlm.nih.gov/18413158/

[9] https://pubmed.ncbi.nlm.nih.gov/16207847/

[10] https://diabetesjournals.org/care/article/26/3/688/29143/Is-the-Current-Definition-for-Diabetes-Relevant-to

[11] https://pubmed.ncbi.nlm.nih.gov/31367697/

[12] https://www.nejm.org/doi/full/10.1056/nejm2e058204

[13] https://link.springer.com/article/10.1007/s00592-007-0249-3

[14] https://pubmed.ncbi.nlm.nih.gov/23453878/

[15] https://pubmed.ncbi.nlm.nih.gov/19563390/

[16] https://pubmed.ncbi.nlm.nih.gov/15277287/

[17] https://www.who.int/en/news-room/fact-sheets/detail/mercury-and-health

[18] https://optimalwellness.net/12677-2/

[19] https://www.rupahealth.com/post/how-functional-medicine-provider-look-at-optimal-lab-ranges#:~:text=Functional%20medicine%20optimal%20ranges%20are,to%20help%20patients%20prevent%20disease.

[20] https://drruscio.com/blood-test-for-health-functional-ranges-versus-lab-ranges/

[21] https://dralexisshields.com/blood-testing-basics

[22] https://www.functionalmedicinecenter.com/functional-lab-and-pathological-ranges/


- https://bloodsmart.ai/bibliography/5f7c75ce5de74e00843440d3

- https://academic.oup.com/ije/article/30/3/427/736897

- https://chriskresser.com/when-your-normal-blood-sugar-isnt-normal-part-2/

Ranodeep Seth
Content Writer

An IT graduate, Ranodeep has worked in IT operations and as a tech blog writer in the past. He is very passionate about health, owing partly to his own chronic health issues which plunged him much deeper into the field. He works for iThrive both as a writer and in the software design team. He is a strong advocate for “informed consent” in healthcare and aims to promulgate the same through his work.

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