From the Research
Functional medicine often uses narrower "optimal" ranges for metabolic markers compared to conventional "normal" ranges, aiming to prevent disease before it develops, as seen in the example of fasting glucose, where functional medicine targets 75-85 mg/dL, unlike conventional medicine which considers 70-99 mg/dL as normal 1.
Optimal Ranges for Metabolic Markers
The concept of optimal ranges in functional medicine is crucial for early intervention and prevention of chronic diseases. Some key examples include:
- Fasting glucose: 75-85 mg/dL, as opposed to the conventional range of 70-99 mg/dL, to prevent insulin resistance 1
- Vitamin D: 50-80 ng/mL, whereas conventional ranges consider 30-100 ng/mL sufficient, for optimal immune function and bone health
- Thyroid function (TSH): 1.0-2.0 mIU/L, unlike conventional ranges of 0.5-4.5 mIU/L, for optimal metabolism
- Hemoglobin A1c: below 5.3%, as opposed to the conventional definition of below 5.7%, to catch metabolic issues earlier and prevent progression to clinical disease 1 These optimal ranges are based on the most recent and highest quality studies, such as the one published in 2022, which highlights the importance of considering liver and chronic kidney disease when interpreting hemoglobin A1c concentrations 1.
Rationale Behind Optimal Ranges
The rationale behind using optimal ranges in functional medicine is to identify subtle imbalances before they progress to clinical disease, reflecting a preventive approach. Many people with values in the "normal" range still experience symptoms or subclinical dysfunction that could benefit from earlier intervention through lifestyle modifications or targeted supplementation. By using narrower optimal ranges, functional medicine practitioners can provide more personalized and effective care, improving patient outcomes and quality of life.
Clinical Implications
The use of optimal ranges in functional medicine has significant clinical implications, including earlier detection and prevention of chronic diseases, improved patient outcomes, and enhanced quality of life. By considering the optimal ranges for metabolic markers, healthcare practitioners can provide more targeted and effective interventions, reducing the risk of disease progression and improving overall health. As seen in the study published in 2022, considering the optimal ranges for hemoglobin A1c can help identify patients with liver and chronic kidney disease, allowing for earlier intervention and improved management of these conditions 1.