Dr. Reed Jarvis, DC | Owner & Chiropractor, The Resilience Lab | Louisville, TN
Most people have had blood work done at some point. You go in for a physical, your doctor orders a standard panel, and a few days later you get a call or a message that says everything looks normal. You feel relieved. Or sometimes you feel confused because you still don't feel good and your labs came back fine.
That gap between normal labs and feeling genuinely well is where functional lab testing lives.
What standard blood work is designed to do
Standard lab panels are designed to detect disease. A complete blood count screens for anemia and infection. A basic metabolic panel checks kidney and liver function, electrolytes, and blood glucose. A lipid panel measures cholesterol and triglycerides. Thyroid-stimulating hormone flags overt thyroid dysfunction. These are valuable tests and they serve an important purpose.
The problem is they measure against population reference ranges, which are statistical averages derived from large populations that include people across a wide spectrum of health. You can fall well within the normal range on every marker and still be functioning suboptimally. Normal doesn't mean optimal. It means you don't have the disease that test was designed to detect.
For someone dealing with chronic fatigue, poor recovery, persistent inflammation, brain fog, hormonal symptoms, or unexplained pain, standard labs often come back normal while the underlying drivers remain completely unaddressed.
What functional lab testing does differently
Functional lab testing shifts the question from "Do you have a disease?" to "How is your body actually functioning?" It looks at a broader set of markers, uses tighter optimal ranges rather than population-based reference ranges, and focuses on identifying patterns and imbalances before they progress into diagnosable conditions.
The philosophy is that health exists on a spectrum. There is a significant distance between diagnosable disease and genuinely optimal function, and that space is where most people spend years not feeling the way they want to feel but being told everything is fine. Functional testing is designed to illuminate what's happening in that space.
What we look at in functional testing
The specific markers we run depend on the patient's presentation, history, and goals. Here are some of the key areas we assess:
Metabolic function and blood sugar regulation
Beyond basic glucose, we look at HbA1c for long-term glucose trends, fasting insulin to assess insulin resistance before blood sugar becomes overtly elevated, and inflammatory markers including high-sensitivity CRP that signal systemic inflammation often driven by poor metabolic health.
Hormone panels
Standard TSH alone is an incomplete picture of thyroid function. A full thyroid panel including free T3, free T4, reverse T3, and thyroid antibodies tells a much more complete story about how the thyroid is actually performing. Sex hormones, testosterone, estrogen, progesterone, and DHEA, along with cortisol rhythms, explain fatigue, mood changes, body composition shifts, and recovery capacity that routine bloodwork routinely misses.
Nutrient status
Subtle deficiencies in vitamin D, magnesium, B12, iron, and other key nutrients create downstream effects on energy, immune function, sleep, and musculoskeletal health that never show up on a standard panel. A significant portion of people presenting with chronic fatigue or poor recovery are chronically low in one or more of these markers.
Inflammatory markers
Beyond basic CRP, we look at markers that give a more granular picture of inflammatory status and its drivers, which inform both lifestyle and nutritional recommendations.
Why this matters for active adults and performance
For someone training consistently, competing, or simply trying to perform well in their daily life, the difference between normal and optimal matters enormously. Suboptimal testosterone impacts recovery, strength adaptation, and body composition. Low vitamin D impairs muscle function, immune response, and bone health. Poor insulin sensitivity slows the body's ability to utilize fuel efficiently and drives the chronic low-grade inflammation that impairs tissue healing.
The athletes and active adults who perform at their best over the long term are not just training hard. They're managing the full picture. Lab data gives us an objective window into how the body is responding to training load, stress, nutrition, and sleep, and where the gaps are that might be holding performance or recovery back.
How we use functional labs at The Resilience Lab
Functional lab testing at The Resilience Lab is not something we run on every patient. It's indicated when the clinical picture suggests that systemic factors like hormonal imbalance, nutrient deficiency, metabolic dysfunction, or chronic inflammation are contributing to a patient's presentation and it's worth getting objective data to guide the approach.
When we do run labs, the results become part of the care plan. Not just a list of numbers with a printed reference range, but a conversation about what the patterns mean, what lifestyle and nutritional factors are likely driving them, and what we can do to move the markers and feel the difference.
