ALTAlanine aminotransferase · SGPT

ALT (alanine aminotransferase) is an enzyme concentrated inside liver cells. When those cells are damaged or under strain, ALT leaks into the bloodstream, so a raised level points toward the liver.

It matters because ALT is a sensitive, everyday flag for liver stress — most commonly from non-alcoholic fatty liver disease, which tracks with metabolic health, but also from alcohol, medication and viral causes. It is one of the more actionable liver markers.

In practice, ALT is read alongside other liver enzymes such as alkaline phosphatase; a mildly raised value is common and usually followed up in the context of weight, alcohol and metabolic health rather than treated in isolation.