Plasma A-beta 42 to A-beta 40 Ratio (A-beta 42/40)
Mathematical ratio of plasma A-beta 42 to A-beta 40 measured via high-resolution immunoprecipitation mass spectrometry (IP-MS).
Standard vs. Optimal Reference RangesRatio
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.
>0.090 (mass spectrometry ratio)
General reference distribution across unselected commercial populations.
>0.100 (amyloid negative)
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Sequestration of A-beta 42 into cortical senile plaques selectively lowers plasma A-beta 42 while A-beta 40 remains unchanged, dropping the ratio.
Differential Diagnosis
Elevated Levels (A-beta 42/40 High)
- •Amyloid-negative brain status (>0.095)
- •Absence of cortical amyloid pathology
Low Levels (A-beta 42/40 Low)
- •High cortical amyloid plaque burden (ratio <0.082)
- •Active Alzheimer disease pathophysiological cascade
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 A-beta 42/40
- Targeted organ system imaging or functional dynamic testing related to cortical amyloid plaque deposition
- Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
- [1]Clinical Reference and Molecular Physiology of Plasma A-beta 42 to A-beta 40 Ratio - The New England Journal of Medicine (2021). PMID: 34190124
- [2]A-beta 42/40 Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35422901
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Plasma A-beta 42 to A-beta 40 Ratio (A-beta 42/40) into overall healthspan optimization.