ALT is an enzyme found mostly in your liver. When liver cells are injured, ALT leaks into the blood, so the test is used as a marker of liver health. Here is how to read your ALT result, in plain language.
ALT stands for alanine aminotransferase, an enzyme concentrated in liver cells. It helps the liver do its everyday chemistry. When liver cells are damaged or inflamed, some ALT escapes into the bloodstream, so a higher blood level can be a signal that the liver is under stress.
ALT is reported in units per litre (U/L). Normal ranges differ noticeably between laboratories, so always read your result against the reference range printed on your own report. A commonly cited range is around 7 to 55 U/L, but your lab may use different cut-offs. Mild elevations are common and are not automatically a sign of serious disease.
A raised ALT points to liver-cell irritation, which has many possible causes, including fatty liver, certain medicines, alcohol, and viral infections. ALT is usually read together with AST and other liver tests to see the pattern. Because a single number rarely tells the whole story, your clinician often repeats the panel and looks at the trend.
Upload a photo or PDF of your liver panel and Mednex reads your ALT and the rest back to you in plain language, then tracks it so your next result compares against this one.
Decode my labsContent last reviewed 9 July 2026. Reference ranges vary by laboratory; always read your results against the range printed on your own report.
This page explains a common lab marker in general terms using public information from the U.S. National Library of Medicine and other NIH sources. It is educational and is not a diagnosis or medical advice. Reference ranges differ between laboratories and the meaning of a result depends on your age, sex, medications, and overall health. Always discuss your own results with the clinician who ordered them.