Is my ALT (Alanine Aminotransferase) normal?
Free blood test checker · Standard + longevity-optimal ranges
What is a normal ALT level?
ALT is the most liver-specific enzyme. Unlike AST, elevated ALT almost always points to the liver. It's the primary screening marker for fatty liver disease (NAFLD), which affects ~25% of adults globally. Normal is below 35 U/L, but longevity physicians prefer below 25 U/L.
| Range | Values |
|---|---|
| Standard Reference | 7–35 U/L |
| Optimal | 7–30 U/L |
| Longevity Optimal | < 25 U/L |
| High Risk | > 50 U/L |
What causes abnormal ALT levels?
Elevated ALT is most commonly caused by non-alcoholic fatty liver disease (NAFLD, affecting ~25% of adults), excess alcohol intake, viral hepatitis (B and C), medications (especially acetaminophen, statins, and antibiotics), obesity, and metabolic syndrome. Even moderate doses of acetaminophen combined with alcohol can spike ALT significantly.
When should you see a doctor?
See your doctor if ALT is persistently above 40 U/L, if you have risk factors for liver disease (obesity, alcohol use, diabetes), or if you notice symptoms like fatigue, nausea, or right-upper-quadrant abdominal pain. Your doctor may order additional tests including GGT, bilirubin, and an ultrasound.
Where to get a ALT test
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Related biomarkers
These biomarkers are often tested alongside ALT for a more complete picture.
Frequently asked questions
What is a normal ALT level?
What does high ALT mean?
How can I lower my ALT naturally?
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Sources: Reference ranges based on AHA/ACC, ADA, and AACE clinical guidelines. Biological variation data from Ricos/Westgard database. Longevity-optimal ranges reflect targets used by preventive and functional medicine practitioners.
Last reviewed: April 2026. This tool provides general health information and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider about your specific results.