Pros and Cons of Functional Lab Testing.

What is Functional Lab Testing?Listen to Healing SIBO and IBS with Better Health by Monica

What is Functional Lab Testing, and what are the pros and cons you need to know as a patient?

Lab testing is lab testing (I promise I’ll elaborate). 

You collect a specimen, send it to a lab for analysis and wait for results about your body, right?

We are all familiar with the blood test we do at our medical doctor’s office. They test for white blood cell count, cholesterol, thyroid, liver enzymes, etc. But lab testing goes way beyond your doctor’s office and way beyond blood testing. Functional medicine doctors, Naturopaths, Health Coaches, and practitioners of all sorts utilize functional lab testing in their practice.

So what is it?

Many private lab companies throughout the U.S. and worldwide offer at-home test kits to collect different types of specimens like stool for microbiome testing, urine for hormone and organic acids, and hair for mineral and heavy metal testing. But these tests are not all equal in quality, efficacy, consistency, or interpretation. 


Here are some pros and cons to Functional Lab Testing or lab testing done privately outside of the doctor’s office. Some medical doctors utilize these types of tests but it is not common to my understanding. 

  1. Gain More Information About the body
  1. Gain more functional information about the body

A high-quality lab test will offer more insight into how the body functions compared to standard blood testing. For example, testing for steroid or sex hormones using dried urine gives insight into real-time production of hormones. A person can collect several samples throughout the day, which reveal more about adrenal dysfunction and circadian rhythm. Specimen matters when investigating certain physiological factors as well as the timing of collection. Taking one blood sample will not provide as much information or correlation. 

  1. Convenience

These lab kits are shipped directly to a client’s home. They can complete them in the comfort of their home at their leisure. Some tests require several samples throughout a day, so a person can plan to collect samples on days convenient. They arrive with shipping labels making it easy for the client to return.

  1. Relevant Lab Ranges

What determines a “healthy test result?”

We are conditioned to think that lab test results are either good or bad. Either you are in range or out of range. Either you have diabetes or don’t. You have cardiovascular disease or don’t. 

Functional Lab Testing tries to provide “healthy” or “optimal ranges.”

When you get blood work back from your doctor, that determines what category of disease you are in; not sick, almost sick, sick. Those results are relative to the entire population. They come up with those ranges based on everybody they’ve ever tested. But we don’t want to be healthy relative to everyone else. We want to be healthy compared to a healthy population, or we want our results to fall where healthy people’s results fall. 

Some labs and independent organizations like Functional Diagnostic Nutrition create their own lab ranges for a specific test to have a better idea of where clients stand on the disease spectrum and where we want our clients to end up.

  1. Correlation

Because these tests offer more info about physiology, deficiencies, and the function of the body systems, they can provide a lot of correlation. In other words, more answers. The results have the potential to answer questions about why a person feels the way they do. This may provide reassurance that experienced pain and suffering is not in a person’s head. It is real and justified. The results can also give a practitioner clues as to what may be causing malfunction.

*SIDE NOTE: These tests are not really meant to “diagnose.”

When you get tested by your doc, they may diagnose you with autoimmune disease, diabetes, etc., based on your test results and then follow up with a protocol for that disease.

A good practitioner will use the results to treat the person rather than the disease. They will refer you to see a doctor because they are not legally allowed to diagnose, but that is not their intent anyway. The results are a part of a bigger picture. They are pieces to the puzzle of your health and may reveal weak links in the body so a practitioner can direct a healing protocol appropriately. 

To recap, Functional Lab Testing (FLT)  can offer more insight into the body’s function by using the appropriate specimen and real-time samples. It is more convenient than going to a lab. It makes collecting several samples easy, and shipping is simple. FLT offers a different perspective on lab ranges by creating “ideal lab ranges” so a person knows where they stand on the metabolic disease spectrum. 

Lastly, FLT offers the most correlation and possibly the WHY behind their symptoms. This is huge for a person who feels they have no answers.

Now let’s talk about the CONS of Functional Lab Testing

  1. Inconsistency and Unreliability

If I were to take a certain test every day for a week or every week for a month would I get the same results?

Our bodies are always changing, so there will be some discrepancies even with high-quality tests, but it is important to find lab tests with the most consistency.

This is where most of the controversy lies with FLT. Tests like IgG Food Sensitivity, Stool testing, and breath testing have all been scrutinized for inconsistency and unreliability. Breath Testing for SIBO has a few studies showing it provides false negatives.

IgG tests have shown major inconsistencies.

And stool testing comes in many different forms (PCR, Culture) and has its fair share of skepticism.

With all that considered, many tests have shown consistency and reliability. Also, I can find studies to support negative claims and studies supporting positive claims about the same tests.

We have to consider the variables of these studies before writing a lab test off. It all comes down to the kind of investigation you need for your body and finding the right test for you.

If you are not sure what tests are best, talk to your practitioner.

  1. Room for biases and conflict of interest in studies

Some lab companies perform internal studies on the lab tests they sell. This means they conduct their own research proving their efficacy. There is a possibility that bias and manipulation will impact analysis. It is important to note that this is not always the case, though. Some labs perform their studies because they have the resources, and their products and tests are very effective and reliable. Labs that prove their efficacy are not all bad, but there have been cases where companies have been sued for manipulating research. The labs that are most transparent get my business. 

  1. Expensive

Lab testing is not cheap. It is easy to rack up a huge bill when running a lot of tests. Testing can be beneficial and prevent someone from continuing trial and error cycles, but you don’t want to over-test. Sometimes it is not necessary to run a bunch of tests right away. In my opinion, it depends on your metabolic state. You may be more inclined to test if you are very sick or are curious to know about your body. Each practitioner has their own stance on this and their own experience with clients. Investing in your health is necessary to heal but make sure you feel confident about which lab tests are right. 

Cons for FLT are potential inconsistency and unreliability, room for conflict of interest in the science, and expensive.

With all that said, I am an advocate for TEST DON’T GUESS. I believe testing responsibly will benefit a client in the long run. The tests allow me to design protocols that address specific dysfunction and support my clients where they need it most. Testing in a holistic paradigm is a tool. It is not used to diagnose, and it really comes down to interpretation and the actions taken after the result comes in.

As a client, you get answers. You may feel crazy because you feel pain and discomfort with no reason why. We know you are not crazy, and the lab tests can provide reassurance that your experience is not “all in your head.” We see the dysfunction on paper.

The most valuable part of my healing journey was gaining self-knowledge and education about my own body. These tests provided me with that self-knowledge and motivated me to change my health for the better, so the next time I tested, I could FEEL and SEE improvement.

Published by monicaboyle

I am a Health Coach and Pilates instructor. I strive to help people find their food freedom and digestive relief so they can become limitless!

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