Picture this. You feel unwell, you can’t quite pinpoint why, but you know something is just not right. Maybe it's hormones or a possible mineral or vitamin deficiency. Whatever it is, you just can’t shake the feeling that something is off. You go see your primary care provider, and they run the standard labs. The doctor comes in and says, “all of your lab results are normal.”
How can this be? Your body is telling you something is wrong, and yet standard lab reference ranges say you are “normal”.
This is where Functional Medicine can be helpful. Functional Medicine Practitioners don’t always focus on standard lab ranges. They more commonly use “optimal” lab values, which can show patterns in the body at the cellular level, potentially years before a patient is diagnosed with a disease.
In this article, we are going to compare some optimal ranges vs standard lab ranges on four commonly ordered functional medicine tests. But before we begin, we should really narrow down the difference between the allopathic standard lab values versus functional medicine “optimal” lab values.
Standard Lab Ranges
Standard lab reference ranges are broad reference ranges used by the laboratories that analyze samples based on averages of a healthy population. These tests help doctors make decisions based on high or low values, but they don’t always tell you what’s optimal.
Lab test results can fall within the normal reference range in the early stages of health issues due to such a wide reference range on standard lab tests. This can lead to cellular patterns in the body being overlooked.
Functional Medicine Optimal Range
Functional Medicine lab ranges are usually much narrower than standard lab ranges. They are labeled “optimal lab values,” meaning anything outside of those optimal values can show patterns and markers that spot trends toward health issues. By catching these markers early on, functional medicine practitioners have a chance at supporting health and wellness.
Below is a comparison on four commonly ordered lab tests and the difference between how functional medicine practitioners look at them vs allopathic standard reference ranges.
Thyroid
Most doctors will only test for TSH when assessing thyroid function. While TSH is an excellent thyroid marker, it only points to general patterns of the thyroid. Without the rest of the thyroid markers, it provides very little value of where the actual pattern is coming from.
A Full thyroid evaluation should include:
- TSH
- Total and free T3 and T4
- T3 Uptake
- Reverse T3
Reference Range for TSH
Standard Reference Range: 0.45-4.12 mlU/L
Functional Medicine Optimal Range: TSH of 0.5-2.5 mlU/L
Reference Range for T3
Standard Reference Range: 2.8-4.0 mlU/L
Functional Medicine Optimal Range: 2.8-4.0 mlU/L
Reference Range for T4
Standard Reference Range: 0.93-1.70 mlU/L
Functional Medicine Optimal Range: 0.93-1.70 mlU/L
Reference Range for Reverse T3
Standard Reference Range: 8-25 ng/dl
Functional Medicine Optimal Range: Less than 15 ng/dl
Top Functional Medicine Complete Thyroid Panels Ordered Through Rupa Health
Boston Heart Diagnostics
Doctors Data
Vitamin D
Vitamin D comes from three main sources: sun exposure, diet, and supplements.
Even with adequate sun exposure and a varied diet, vitamin D deficiency is prevalent and affects over 40% of people in North America.
Vitamin D levels are associated with several health concerns, including bone health and immune function. Functional Medicine practitioners like to see Vitamin D levels slightly higher than allopathic doctors. Research shows that higher levels of vitamin D may help support a healthy inflammatory response and are associated with overall wellness.
Testing for Vitamin D is quite simple, and most labs offer a blood spot option that patients can do from the comfort of their own homes.
Reference Range for Vitamin D
Standard Reference Range: 20 and 40 ng/mL
Functional Medicine Optimal Range: 40-70 ng/mL
Top 3 Functional Medicine Vitamin D Test Ordered Through Rupa Health
Ayumetrix
US BioTek
Mosaic Diagnostics
Insulin
Insulin resistance currently affects 1 in 3 Americans and is a precursor to prediabetes and eventually type 2 diabetes if not managed through nutrition and lifestyle intervention.
There is no one lab test that can directly screen for insulin resistance, but looking at the entire clinical picture alongside labs can show patterns in cellular glucose metabolism long before one actually develops diabetes. Therefore, it is important to screen for evidence of glucose dysregulation as early as possible.
Insulin resistance (IR) marks the beginning of these metabolic changes and can be detected via blood work, glucose tolerance tests, or continuous glucose monitors.
Reference Range for Hgba1c
Hgba1c is a blood test that measures your average blood sugar levels over the past three months using a percentage point.
Standard Reference Range: Under 5.7
Functional Medicine Optimal Range: 4.6-5.5
Reference Range for Fasting Insulin
Insulin resistance is characterized by increased insulin levels in the blood.
Standard Reference Range: 2.6-24.9 mcIU/ml
Functional Medicine Optimal Range: 4.6 – 5.5 mcIU/ml
Reference Range for Fasting Glucose
This is a measure of how much glucose (sugar) is in your blood after an overnight fast.
Standard Reference Range: 70 – 125 mg/dL
Functional Medicine Optimal Range: 70- 85 mg/dL
Top 3 Functional Medicine Insulin Resistance Test Ordered Through Rupa Health
Ayumetrix
ZRT
Access Medical Laboratories
Cortisol
Cortisol follows a circadian rhythm starting with the cortisol awakening response (CAR) upon waking. Cortisol should be highest in the morning and lowest during the evening. But cortisol can rise and be out of balance during the day due to stress, chronic pain, and blood sugar dysregulation.
Long-term high cortisol levels throughout the day can be associated with weight changes, sleep disturbances, temperature fluctuations, and fatigue.
Most traditional doctors will test cortisol in the am, only getting a direct read on morning cortisol levels. But this does the patient no good if their cortisol levels are fluctuating throughout the day.
Functional medicine providers will normally test cortisol throughout the day with four different salivary samples. This type of testing gives insight into the natural circadian daily cortisol rhythm and helps clinicians address the time that specific daily stressors are occurring.
Reference Range for Cortisol
8am to 12pm: 5-25 mcg/dL
Functional medicine optimal ranges can change based on the specialty lab used. Each lab test will guide you through the exact time slots to measure. These tests are usually done via salivary testing and can be done at the patient’s home.
Two important things to keep in mind for cortisol awakening response are:
- Cortisol should be highest 30 mins after waking and should continue to drop throughout the day. There should be no peaks throughout the day.
- Use a test that allows multiple samples throughout the day, including morning, midday, afternoon, and evening.
Top 3 Functional Medicine Cortisol Awakening Response Test Ordered Through Rupa Health
Genova Diagnostics
Doctor's Data/Labrix
ZRT
Summary
Most standard lab reference ranges are very wide, allowing health issues to possibly go undetected. Functional medicine optimal ranges are usually much narrower, allowing practitioners to foresee possible patterns so they may intervene early with nutrition, supplements, and lifestyle adjustments to help patients support their health.
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