Aspartate Aminotransferase (AST)
Aspartate aminotransferase exists in both mitochondrial (80%) and cytosolic (20%) isoenzyme forms across hepatocytes, cardiac myocytes, and skeletal muscle tissue.
Standard vs. Optimal Reference RangesU/L
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.
8 - 48 U/L
General reference distribution across unselected commercial populations.
15 - 25 U/L
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
AST catalyzes the conversion of aspartate and alpha-ketoglutarate into oxaloacetate and glutamate. While present in liver, high concentrations reside in cardiac and skeletal muscle, meaning intense resistance exercise frequently elevates AST independently of liver pathology.
Differential Diagnosis
Elevated Levels (AST High)
- •Alcoholic liver disease (mitochondrial toxicity)
- •Intense eccentric resistance training / Rhabdomyolysis
- •Myocardial infarction
- •Cirrhosis and advanced fibrosis
Low Levels (AST Low)
- •Absence of tissue injury
- •Vitamin B6 deficiency
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
A 12-hour overnight fast is recommended, especially if assessing biliary markers or lipid-associated hepatic enzymes. Complete abstinence from ethanol for at least 48 to 72 hours prior to testing is mandatory to prevent enzyme induction. Avoid strenuous unaccustomed weightlifting for 48 hours prior, which can release muscular transaminases and elevate AST/ALT.
Reflexive Testing Protocol:
- Comprehensive Hepatic Viral Panel (Hepatitis A IgM, HBsAg, HBcAb, HCV antibody with reflex PCR)
- Vibration-Controlled Transient Elastography (FibroScan) or Magnetic Resonance Elastography to quantify hepatic fat and fibrosis
- Serum Ferritin and Total Iron-Binding Capacity (TIBC) to screen for hereditary hemochromatosis
- Autoimmune Liver Disease Serology (Anti-Nuclear Antibodies, Anti-Smooth Muscle Antibodies, Anti-Mitochondrial Antibodies)
- Abdominal Right Upper Quadrant Ultrasound to assess hepatic parenchyma, biliary ducts, and portal vein flow
Clinical Citations & Primary Literature (1)
- [1]Clinical Interpretation of Liver Enzymes: AST, ALT, and GGT - American Journal of Gastroenterology (2021). PMID: 33417942
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Aspartate Aminotransferase (AST) into overall healthspan optimization.