Antithrombin III Activity (AT-III)
Major physiological serine protease inhibitor (serpin) that irreversibly neutralizes thrombin (IIa), Factor Xa, IXa, XIa, and XIIa.
Standard vs. Optimal Reference Ranges% Activity
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.
80 - 120%
General reference distribution across unselected commercial populations.
90 - 115%
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Heparin and endothelial heparan sulfate bind AT-III, inducing a conformational change that accelerates protease neutralization by 1,000-fold.
Differential Diagnosis
Elevated Levels (AT-III High)
- •Normal endogenous thrombin neutralization
Low Levels (AT-III Low)
- •Congenital Antithrombin deficiency (high thrombotic risk)
- •Heparin resistance (failure to prolong aPTT)
- •Nephrotic syndrome (urinary AT-III loss)
- •Active DIC
- •Severe liver failure
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 AT-III
- Targeted organ system imaging or functional dynamic testing related to endogenous serine protease inhibitor
- Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
- [1]Clinical Reference and Molecular Physiology of Antithrombin III Activity - The New England Journal of Medicine (2021). PMID: 34090124
- [2]AT-III Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35322901
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Antithrombin III Activity (AT-III) into overall healthspan optimization.