ALT
A liver enzyme — the primary marker of liver cell injury.
What is it
ALT is an enzyme found primarily in liver cells. When liver cells are injured, ALT is released into the blood, making it a primary marker of hepatocellular injury.
Why it's measured
Elevated ALT has been associated with fatty liver disease, viral hepatitis, and medication-related liver injury in published research.
Reference range
Standard laboratory reference
< 40 U/L
Reference ranges vary by laboratory. Your individual reference range will appear on your test report and should be interpreted by your physician in the context of your overall health profile.
What results may indicate
Elevated
Has been associated with hepatocellular injury including fatty liver disease and viral hepatitis in research literature.
Lower
Is generally considered favorable.
These associations are general. They are not a personal diagnosis or prediction. Discuss your individual results with your physician in the context of your full health profile.
When it's measured
Part of every standard liver panel and routine physical.
Related markers
Common questions
ALT is an enzyme found primarily in liver cells. When liver cells are injured, ALT is released into the blood, making it a primary marker of hepatocellular injury.
It's one of the markers used to build a fuller picture of your health. On its own it tells you very little, so it's most informative when reviewed alongside related markers.
It's measured from a standard blood draw at Quest or LabCorp. ALT (Alanine Aminotransferase) is one of the markers included in the OPTML Apex Panel, where your results are read across systems and reviewed by a U.S.-licensed physician.
Reference ranges vary by laboratory, and a single value rarely tells the whole story. Review your result with a physician in the context of your other markers, symptoms, and history.
ALT (Alanine Aminotransferase) is one signal among many. Answer a few quick questions and we’ll point you to the panel that fits.
Measured in
A complete look at your heart, hormones, metabolism, inflammation, and longevity systems — drawn at Quest or LabCorp, reviewed by a U.S.-licensed physician.
Explore the Apex Panel →This information is for general educational purposes only and is not medical advice. Lab results alone are not intended to diagnose, treat, or cure any condition and do not replace the advice of a healthcare provider. OPTML does not offer medical advice, a diagnosis, medical treatment, or any form of medical opinion.