ALT (Alanine Aminotransferase)
Enzyme that indicates liver health
21 of 22 providers
Liver Function
fatty liver disease
What is ALT (Alanine Aminotransferase)?
ALT (Alanine Aminotransferase) is an enzyme found primarily in your liver cells. When liver cells are damaged or inflamed, ALT leaks into your bloodstream, making it one of the most specific and sensitive markers for liver cell injury.
Unlike other liver enzymes like AST (which is also found in heart and muscle tissue), ALT is highly concentrated in the liver, which makes it the most specific indicator of hepatocellular damage. This specificity makes ALT the go-to marker for detecting conditions like fatty liver disease, viral hepatitis, medication-induced liver injury, and other forms of liver inflammation.
ALT is typically measured as part of a comprehensive metabolic panel or liver function tests. While conventional reference ranges often extend up to 40-55 U/L, research shows that optimal levels for longevity and metabolic health are much lower, typically under 25-30 U/L for men and under 20-25 U/L for women.
Why ALT Is Your Most Important Liver Health Marker
- Most specific liver enzyme:ALT is predominantly found in liver cells, making it more specific for liver damage than AST or ALP
- Early detection of fatty liver:Even mildly elevated ALT (25-40 U/L) often indicates non-alcoholic fatty liver disease (NAFLD), which affects 25-30% of adults
- Metabolic health indicator:ALT correlates strongly with insulin resistance, obesity, and metabolic syndrome
- Cardiovascular risk marker:Elevated ALT predicts increased risk of heart disease, stroke, and type 2 diabetes
- Reversible with lifestyle:Unlike advanced liver disease, early ALT elevation can be normalized through diet, exercise, and weight loss
Optimal vs Standard Ranges
Optimal (Longevity)Men:<25 U/L, Women:<20 U/L▼
- Associated with lowest metabolic disease risk and optimal liver health
- Studies show ALT below these levels correlates with reduced cardiovascular events, lower diabetes risk, and better overall longevity
- This is the target range for health optimization
Borderline ElevatedMen:25-40 U/L, Women:20-35 U/L▼
- Often still within "normal"lab range but indicates early metabolic dysfunction or mild fatty liver
- This range warrants lifestyle intervention, weight loss if overweight, and investigation of underlying causes
- Retest in 3-6 months after implementing changes
Moderately Elevated40-100 U/L▼
- Indicates significant liver inflammation or damage
- Common causes include NAFLD, alcohol consumption, viral hepatitis, or medication toxicity
- Requires medical evaluation, liver imaging (ultrasound), and investigation of underlying cause
- Consider checking AST, GGT, and hepatitis panel
Severely Elevated>100 U/L▼
- Indicates acute or severe liver injury
- Levels >1000 U/L suggest acute hepatitis (viral, drug-induced, or autoimmune) or ischemic liver injury
- Requires immediate medical attention, comprehensive liver workup including viral hepatitis panel, autoimmune markers, and imaging
- Very high levels (>10,000) can indicate acute liver failure
Scientific Evidence
Lower ALT Thresholds Predict Disease
Large population studies show that even ALT levels in the "high-normal"range (30-40 U/L) are associated with increased risk of liver disease progression, metabolic syndrome, and cardiovascular events. The optimal upper limit for ALT is likely 25-30 U/L for men and 20-25 U/L for women, much lower than conventional reference ranges.
ALT and Cardiovascular Risk
Meta-analyses demonstrate that elevated ALT independently predicts cardiovascular disease, stroke, and all-cause mortality. Each 5 U/L increase in ALT is associated with 15% higher risk of cardiovascular events. This relationship holds even after adjusting for traditional risk factors like cholesterol and blood pressure.
Weight Loss Reverses Fatty Liver and ALT
Randomized controlled trials show that 7-10% weight loss through caloric restriction and exercise significantly reduces ALT, liver fat content, and even reverses early liver fibrosis in NAFLD patients. The Mediterranean diet combined with exercise is particularly effective, with up to 45% of patients achieving ALT normalization.
Coffee Protects Against Liver Disease
Multiple large cohort studies show that regular coffee consumption (2-3+ cups daily) is associated with lower ALT levels, reduced risk of NAFLD progression to cirrhosis, and lower rates of liver cancer. Both caffeinated and decaffeinated coffee show benefit, suggesting compounds beyond caffeine (like chlorogenic acids) provide liver protection.
Source:Alferink LJ, et al. Coffee and herbal tea consumption is associated with lower liver stiffness in the general population. J Hepatol. 2017;67(2):339-348.
Vitamin E for NASH
The PIVENS trial demonstrated that vitamin E (800 IU daily) significantly improved ALT levels, liver histology, and inflammation in non-diabetic patients with NASH compared to placebo. However, benefits are most pronounced in non-diabetics, and long-term safety requires monitoring.
Source:Sanyal AJ, et al. Pioglitazone, vitamin E, or placebo for nonalcoholic steatohepatitis. N Engl J Med. 2010;362(18):1675-1685.
Which Providers Test ALT (Alanine Aminotransferase)?
Full Provider Comparison
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $444 | 288 | |
| ✓ | $349 | 100+ | |
| ✓ | $761 | 54 | |
 Function Health | ✓ | $365 | 160+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| ✓ | $375 | 80+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| ✓ | $99 | 50 | |
| ✓ | $124 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 70-80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 128 |
Frequently Asked Questions
What is ALT (Alanine Aminotransferase)?
Enzyme that indicates liver health
What is the optimal range for ALT (Alanine Aminotransferase)?
The standard reference range for ALT (Alanine Aminotransferase) is fatty liver disease. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include ALT (Alanine Aminotransferase)?
21 out of 22 blood testing providers include ALT (Alanine Aminotransferase) in their panels. This biomarker is widely available across major providers.
What category does ALT (Alanine Aminotransferase) fall under?
ALT (Alanine Aminotransferase) is categorized under Liver Function. This category includes biomarkers that help assess related aspects of health and wellness.
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:2026-02-20