AST (Aspartate Aminotransferase)
AST is an enzyme found in liver, heart, skeletal muscle, kidney, and red blood cells that enters blood when these tissues are damaged. Elevations can reflect liver disease, muscle injury, heavy exercise, hemolysis, or heart events. The AST/ALT ratio helps differentiate alcoholic liver disease (ratio above 2) from other causes of hepatitis.
Units: U/L. Check the units on your report before comparing to any range here.
Optimal range: who says what
Institutions, researchers and practitioners draw the line in different places. Each position is listed with who holds it and, where a document states it, a link. How we verify ranges.
- Named practitioner<35 U/LOptimal DX · Optimal GGT Levels: More Than a Liver Enzyme
- Named practitioner<35 U/LRupa Health · Interpreting Liver Enzyme Tests: ALT, AST, and ALP
- Lab reference interval10-40 U/LWhat a lab report flags against. A lab interval is not an optimal target.
Practitioner targets are individual positions, often tighter than guideline ranges. Each was checked against its article before publishing.
21 of 21 itemized panels
Liver Function
What is AST (Aspartate Aminotransferase)?
AST (Aspartate Aminotransferase) is an enzyme found in multiple tissues including liver, heart muscle, skeletal muscle, kidneys, and red blood cells. When these tissues are damaged, AST is released into the bloodstream. While less liver-specific than ALT, AST is valuable when interpreted alongside ALT and other markers.
The AST/ALT ratio is particularly diagnostic: A ratio less than 1 (AST lower than ALT) typically indicates non-alcoholic fatty liver disease, while a ratio greater than 2 suggests alcoholic liver disease or advanced cirrhosis. AST is also crucial for detecting heart damage (elevated after heart attacks), muscle injury (rhabdomyolysis), and hemolysis (red blood cell breakdown).
AST exists in two forms: cytoplasmic AST (released with mild injury) and mitochondrial AST (released with severe injury). Very high AST levels (>1000 U/L) suggest acute hepatocellular necrosis from causes like viral hepatitis, drug toxicity, or ischemic injury. Like ALT, optimal AST levels for longevity are lower than conventional reference ranges.
Why AST Matters Beyond the Liver
- Differential diagnosis: AST/ALT ratio helps distinguish alcoholic from non-alcoholic liver disease, and acute from chronic injury
- Multi-organ damage detection: Unlike ALT, elevated AST can indicate heart attack, muscle breakdown, or hemolysis, not just liver disease
- Severity indicator: Very high AST (>10x upper limit) indicates severe acute injury requiring urgent intervention
- Fibrosis progression: Rising AST/ALT ratio over time suggests advancing liver fibrosis or cirrhosis
- Metabolic health marker: Like ALT, elevated AST in the "high-normal" range correlates with insulin resistance and cardiovascular risk
Interpretation bands (curated, PMID-backed)
Holder: OptimizeBiomarkers editorial synthesis of: Loss of Life Expectancy by 10 Years or More From Elevated Aspartate Aminotransferase: Finding Aspartate Aminotransferase a Better Mortality Predictor for All-Cause and Liver-Related than Alanine Aminotransferase (Xie et al., 2019); Serum aminotransferase activity and mortality risk in a United States community (Lee et al., 2008). No single paper sets these cutoffs; for attributed targets see who says what.
Optimal (Longevity)Men: <25 U/L, Women: <20 U/L▼
- Associated with optimal metabolic health and lowest cardiovascular risk
- Studies show these levels correlate with reduced mortality and better long-term health outcomes
- Maintain AST/ALT ratio between 0.8-1.3 for optimal health
Borderline ElevatedMen: 25-40 U/L, Women: 20-35 U/L▼
- Often within standard reference range but may indicate early metabolic dysfunction, mild fatty liver, or subclinical muscle/heart issues
- Check AST/ALT ratio and consider lifestyle modifications
- Retest in 3-6 months
Moderately Elevated40-150 U/L▼
- Indicates tissue damage requiring investigation
- Check ALT, CK (creatine kinase for muscle), troponin (for heart), and liver imaging
- If AST/ALT ratio >2, consider alcohol use or advanced liver disease
- If AST elevated alone with normal ALT, consider heart or muscle source
Severely Elevated>150 U/L▼
- Indicates significant acute injury
- Levels >1000 U/L suggest acute hepatitis, drug-induced liver injury, ischemic hepatitis, or myocardial infarction
- Requires urgent medical evaluation, comprehensive workup including troponin, CK, hepatitis panel, and imaging
- Very high levels (>10,000) indicate massive tissue necrosis
- Loss of Life Expectancy by 10 Years or More From Elevated Aspartate Aminotransferase: Finding Aspartate Aminotransferase a Better Mortality Predictor for All-Cause and Liver-Related than Alanine Aminotransferase.
- Serum aminotransferase activity and mortality risk in a United States community.
- Complex association between alanine aminotransferase activity and mortality in general population: a systematic review and meta-analysis of prospective studies.
What raises or lowers AST
Causes of high AST
- Liver causes: Fatty liver disease (NAFLD/NASH), alcoholic hepatitis (AST/ALT ratio >2), viral hepatitis (A, B, C), drug-induced liver injury, autoimmune hepatitis, cirrhosis (AST often higher than ALT), hemochromatosis, Wilson's disease
- Cardiac causes: Myocardial infarction (heart attack), myocarditis, congestive heart failure, cardiac surgery
- Muscle causes: Rhabdomyolysis (severe muscle breakdown), intense exercise, trauma, statin-induced myopathy, polymyositis/dermatomyositis
- Hemolysis: Red blood cell breakdown from various causes (hemolytic anemia, transfusion reactions)
- Other: Pancreatitis, kidney infarction, burns, heatstroke, celiac disease, hypothyroidism
Causes of low AST
- Vitamin B6 (pyridoxine) deficiency
- Chronic kidney disease, especially with dialysis
- Severe malnutrition or low protein intake
- Rare genetic variants (extremely uncommon)
Symptoms when AST is high or low
When high
Symptoms depend on underlying cause:
- Liver-related: Fatigue, right upper quadrant pain, nausea, jaundice (if bilirubin elevated), dark urine
- Heart-related: Chest pain, shortness of breath, palpitations, arm/jaw pain (if cardiac source)
- Muscle-related: Muscle pain, weakness, dark urine (myoglobin), swelling (if rhabdomyolysis)
- Often asymptomatic: Mild elevations (30-60 U/L) frequently cause no symptoms
Severe elevations (>500 U/L) typically cause more pronounced symptoms and warrant immediate evaluation. Acute onset of symptoms with very high AST requires emergency assessment to rule out heart attack or acute liver failure.
When low
Low AST is uncommon and rarely clinically significant. Possible associations:
- Vitamin B6 deficiency (AST requires pyridoxal phosphate as cofactor)
- Severe kidney disease with uremia
- Rare genetic enzyme deficiencies
- Malnutrition or severe protein deficiency
Low AST typically requires no treatment unless part of broader nutritional deficiency. Ensure adequate B6 intake (1.5-2 mg daily) and balanced protein consumption.
How to move AST
Effect sizes (how much something moves the marker) appear only where the paper cited under the item states them. Talk to your clinician before starting or changing any medication or supplement.
Address Underlying Liver Disease
- Weight loss for NAFLD: 7-10% body weight reduction if overweight (same as ALT)
- Alcohol cessation: If AST/ALT ratio >2, eliminate alcohol completely for 3-6 months and retest
- Treat viral hepatitis: Antiviral therapy for Hepatitis B or C can normalize AST
- Mediterranean diet: Rich in olive oil, fish, vegetables; reduces liver inflammation
- Coffee consumption: 2-3 cups daily associated with lower AST and reduced fibrosis risk
Optimize Cardiovascular and Muscle Health
- If AST elevated with normal ALT, consider cardiac sources: Check troponin, ECG, and consider cardiology referral if chest pain, dyspnea, or cardiac risk factors
- Manage muscle injury: If CK also elevated, identify cause (strenuous exercise, statins, rhabdomyolysis). Hydrate well and avoid intense exercise until normalized
- Statin-induced myopathy: If on statins with elevated AST/CK, consider CoQ10 supplementation (100-200 mg daily) or switch to lower-potency statin
- Address hemolysis: If indirect bilirubin and LDH also elevated, investigate for hemolytic anemia
Reduce Hepatotoxin Exposure
- Limit alcohol: Even moderate drinking can elevate AST, especially in susceptible individuals
- Review medications: Statins, NSAIDs, antibiotics, acetaminophen, and many supplements can elevate AST
- Avoid acetaminophen overdose: Stay under 3000 mg/day; lower if alcohol consumption or other risk factors
- Herbal supplements: Many supplements (green tea extract, anabolic compounds) can cause liver injury
- Environmental toxins: Minimize exposure to pesticides, industrial solvents, and cleaning chemicals
Support Mitochondrial and Liver Health
- Coenzyme Q10: 100-300 mg daily supports mitochondrial function and may reduce statin-related AST elevation
- N-acetylcysteine (NAC): 600-1200 mg daily boosts glutathione, protects against oxidative liver damage
- Vitamin E: 400-800 IU daily (mixed tocopherols) reduces liver inflammation in NASH
- Milk thistle: 140-280 mg 2-3x daily has weak evidence for lowering AST
- Omega-3 fatty acids: 2-4g EPA+DHA daily reduces inflammation and liver fat
Lifestyle Modifications
- Regular exercise: 150+ minutes/week moderate aerobic activity improves liver and cardiovascular health
- Strength training: Builds healthy muscle mass and improves insulin sensitivity, but avoid overtraining
- Adequate hydration: Especially important if muscle damage is suspected
- Quality sleep: 7-9 hours nightly; poor sleep worsens liver disease and metabolic dysfunction
- Stress management: Chronic stress elevates cortisol and can worsen metabolic liver disease
When to retest
- After lifestyle changes: Retest in 8-12 weeks following diet, exercise, and alcohol cessation
- After medication changes: If starting hepatotoxic medication or discontinuing suspected culprit, retest in 4-8 weeks
- If moderately elevated (40-150 U/L): Retest every 3-6 months with comprehensive liver panel (ALT, ALP, GGT, bilirubin) and assess trend
- If severely elevated (>150 U/L): Retest within 1-2 weeks with urgent workup including troponin (cardiac), CK (muscle), hepatitis panel, and imaging
- Monitor AST/ALT ratio: If ratio increases over time (approaching or exceeding 2), suggests advancing fibrosis—consider liver elastography (FibroScan)
- Annual screening: If metabolic risk factors present (obesity, diabetes, alcohol use), check annually
Scientific Evidence
AST/ALT Ratio and Cirrhosis
In 160 patients with primary biliary cirrhosis, the AST/ALT ratio was significantly higher in those with cirrhosis and was associated with esophageal varices and ascites. The ratio helped suggest cirrhosis but did not predict prognosis.
Source: The AST/ALT ratio as an indicator of cirrhosis in patients with PBC.
AST Within the Normal Range and Cardiac Death
In 6,857 patients with coronary artery disease and AST inside the reference range, AST had a U-shaped relationship with 3-year cardiac mortality: compared with 21 U/L, values below 15 U/L and above 23 U/L carried higher risk. After adjustment for other factors the association weakened but stayed non-linear.
Source: Aspartate aminotransferase and mortality in patients with ischemic heart disease.
Which Providers Test AST (Aspartate Aminotransferase)?
Cheapest: Oura Health Panels at $99/year. Most comprehensive: Function Health, 160+ biomarkers for $365/year.
21 panels that include it, cheapest first
| Provider | Annual Cost | Total Biomarkers | $/Biomarker |
|---|---|---|---|
| $99 | 50 | $1.98 | |
| $190 | 100+ | $1.90 | |
| $250 | 65 | $3.85 | |
| $297 | 100+ | $2.97 | |
 Labcorp OnDemand | $338 | 50+ | $6.76 |
 Superpower | $349 | 100+ | $3.49 |
| $349 | 75+ | $4.65 | |
 WHOOP Advanced Labs | $349 | 65 | $5.37 |
 Function Health | $365 | 160+ | $2.28 |
| $365 | 100+ | $3.65 | |
| $375 | 108 | $3.47 | |
| $449 | 83 | $5.41 | |
| $495 | 80+ | $6.19 | |
| $499 | 100+ | $4.99 | |
| $700 | 138 | $5.07 | |
| $829 | 54 | $15.35 | |
| $895 | 100+ | $8.95 | |
| $996 | 59 | $16.88 | |
| $1188 | 70+ | $16.97 | |
| $1198 | 40+ | $29.95 | |
| $1950 | 130+ | $15.00 |
$/Biomarker is annual cost divided by the panel's advertised biomarker count, not the price of this one test. We track 23 blood test providers (32 plans); 21 of those plans are itemized marker by marker. Compare all of them.
11 providers not itemized in our matrix
We have not itemized these marker by marker (some sell tests one at a time), so this page cannot say whether they offer AST (Aspartate Aminotransferase). Check with them directly.
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Experts discussing AST (Aspartate Aminotransferase)
Podcast episodes where clinicians and researchers cover this marker in depth. Curated by hand; an episode is listed only when the marker is a substantial topic, not a passing mention.
- How Insulin Resistance Drives Fatty Liver, Cognitive Issues, and Metabolic SyndromeDisclosure: Hyman co-founded Function Health, which appears in our blood-test comparisons.
- The Best Diet to Reverse Fatty Liver DiseaseDisclosure: Hyman co-founded Function Health, which appears in our blood-test comparisons.
- What's the Deal with Liver Enzymes with Dr. William Carey MD
- Liver Function Testing - What Every Question You've Ever Had
Frequently Asked Questions
What is the optimal range for AST (Aspartate Aminotransferase)?
Named practitioners target: <35 U/L (Optimal DX); <35 U/L (Rupa Health). Lab reference interval: 10-40 U/L. That is what a lab report flags against, not an optimal target.
Which blood test providers include AST (Aspartate Aminotransferase)?
21 of the 21 blood testing panels we itemize marker by marker include AST (Aspartate Aminotransferase) in their panels. This biomarker is widely available across major providers.
Related: YouBoost rates lifestyle and supplement interventions by evidence.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed Sep 23, 2026 · First published Sep 30, 2025