What is ALT?
ALT often increases when liver cells are irritated or damaged, for example due to lifestyle factors, medication, or a temporary inflammatory response. Context (symptoms, alcohol, medication, recent illness) and especially the trend over time are usually more informative than a single value.
Why is ALT relevant?
ALT is one of the most sensitive markers for liver cell stress: as soon as liver cells get irritated or damaged, ALT leaks into the blood and the value rises. Elevations can track with lifestyle (alcohol, overweight), medication, infections, or a fatty-liver pattern. For people who want to see how their liver is coping, ALT is one of the first markers to check.
How to read ALT in context
Read ALT alongside AST, GGT, and bilirubin — only then does the pattern emerge that points toward a cause. Recent intensive exercise can raise AST more than ALT (because AST is also present in muscle), which can skew the ratio. For a fair picture, do not measure straight after heavy training and use the trend across several measurements — an isolated mild elevation is often nothing serious.