What is ALT and what does it tell you about your liver?
ALT is a liver-specific enzyme released when hepatocytes are stressed. Elevations above 25-30 U/L — even inside the lab reference range — warrant context with insulin resistance and central adiposity.
Full answer
ALT (alanine aminotransferase) is the most liver-specific routine enzyme in widespread use. It is released into circulation when hepatocytes are stressed or damaged by NAFLD, viral hepatitis, alcohol, medications, or metabolic disease. The clinical insight oMeds provider review applies: ALT inside the conventional 'normal' range (up to 55 U/L in men, 45 in women) frequently masks early NAFLD. Persistent ALT above 25 U/L, particularly with central adiposity, elevated triglycerides, or rising fasting insulin, is a signal — not noise. ALT is interpreted alongside AST, ALP, GGT, bilirubin, and the metabolic panel. Lifestyle drivers — visceral fat reduction, alcohol moderation, treatment of insulin resistance — typically lower ALT before any pharmacologic intervention is considered.
Educational. Not a substitute for individualized provider review.
- ALT — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29