Alanine aminotransferase (ALT)

What it is

ALT is an enzyme included in liver function testing.^[1,2]

Why it matters

Higher ALT can enter liver-cell injury discussions, but it does not diagnose a specific liver disease by itself.^[1,2]

Root causes of abnormal values

• Physical core: ALT rises when more of this liver-cell enzyme leaks or is released into blood from injured or stressed liver cells; it falls when that leakage signal is lower. ALT is therefore a liver-cell injury signal, not a direct label for one disease.^[1,2]
  Aspartate aminotransferase (AST)BilirubinHepatic steatosisLiver fibrosis
• Pattern layer: ALT is usually read with AST, bilirubin, alkaline phosphatase, albumin, history, and imaging. The pattern can point toward liver-cell injury context, bile-flow context, or synthetic-function context, but the enzyme alone cannot identify the cause.^[1,2]
  Aspartate aminotransferase (AST)BilirubinAlbumin blood level
• Boundary: BioConst can explain ALT as an injury-signal component of a liver panel, but it does not diagnose hepatitis, fatty liver, alcohol-associated injury, medication injury, or any person's liver condition.^[1,2]

What it affects

• ALT is often read with AST, bilirubin, alkaline phosphatase, albumin, history, and imaging context.^[1,2]

Interpretation traps

• A normal or abnormal ALT alone is not a diagnosis or treatment decision.^[1,2]

Related conditions