Brachial Flow-Mediated Dilation (FMD)
High-resolution ultrasound measurement of brachial artery endothelial dilation in response to shear stress-induced nitric oxide release.
Standard vs. Optimal Reference Ranges% Dilation
Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.
Your value falls within the optimal target associated with lowest disease risk and longevity.
>7.0% arterial diameter dilation
General reference distribution across unselected commercial populations.
>10.0% arterial diameter dilation
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Cuff occlusion induces reactive hyperemia; endothelial shear stress activates eNOS phosphorylation (Ser1177) to release nitric oxide.
Differential Diagnosis
Elevated Levels (FMD High)
- •Optimal endothelial nitric oxide bioavailability (>10%)
- •Young athletic cardiovascular status
Low Levels (FMD Low)
- •Endothelial dysfunction (<5%)
- •Atherosclerosis
- •Smoking and metabolic syndrome
- •Hypertension
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Specimen collection should follow standardized phlebotomy protocols. Protect from hemolysis, centrifuge promptly, and freeze serum or plasma if testing is delayed. Patient should be in a resting, fasting state where indicated.
Reflexive Testing Protocol:
- Confirmatory testing and secondary biomarker quantification for FMD
- Targeted organ system imaging or functional dynamic testing related to endothelial nitric oxide function
- Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
- [1]Clinical Reference and Molecular Physiology of Brachial Flow-Mediated Dilation - The New England Journal of Medicine (2021). PMID: 33990124
- [2]FMD Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35222901
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Brachial Flow-Mediated Dilation (FMD) into overall healthspan optimization.