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Guilherme Mazui

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What is the Difference Between ALT and AST?

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ALT (Alanine Transaminase) and AST (Aspartate Transaminase) are two enzymes used in liver function tests to assess liver health. The main differences between them are:

  1. Location: ALT is predominantly found in the liver, while AST is mainly found in the liver, cardiac muscle, and other tissues.
  2. Liver cell injury assessment: The ratio of AST to ALT is commonly used to assess liver cell injury.
  3. AST/ALT ratio interpretation: An AST/ALT ratio of less than one (where the ALT is significantly higher than the AST) may indicate non-alcoholic fatty liver disease. An AST/ALT ratio of more than 1.5 indicates intrahepatic (mechanical or medical) cholestasis is more likely, while an AST/ALT ratio of less than 1.5 suggests extrahepatic biliary obstruction.
  4. Disease association: An AST/ALT ratio greater than 2 is strongly suggestive of alcoholic liver disease, while a ratio less than 1 is more suggestive of non-alcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH).

In summary, ALT and AST are both enzymes used to assess liver health, but they are found in different tissues and have different ratios that can indicate various liver conditions.

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  • What is the Difference Between ALT and AST?
  • Comparative Table: ALT vs AST

    • Comparative Table: ALT vs AST

    ALT and AST are two liver transaminase enzymes that play crucial roles in the liver's function. Here is a table comparing the differences between ALT and AST:

    Feature ALT (Alanine Transaminase) AST (Aspartate Transaminase)
    Function Catalyzes the transfer of an amino group from L-alanine to α-ketoglutarate Catalyzes the transfer of an amino group from L-aspartate to α-ketoglutarate
    Location Primarily found in the liver, but also in skeletal muscle, heart, and kidneys Found in the liver, heart, skeletal muscle, kidneys, brain, and red blood cells
    Specificity More specific indicator of hepatic injury Less specific indicator of hepatic injury
    Common Elevation Causes Liver disease, viral hepatitis, ischemic hepatitis, drug or toxin-induced liver injury Liver disease, viral hepatitis, ischemic hepatitis, drug or toxin-induced liver injury
    Other Elevation Causes Muscle damage, disease, or use of certain drugs Heart attack, acute pancreatitis, or some infections

    An AST/ALT ratio higher than one (where the AST is higher than ALT) may indicate cirrhosis. ALT is higher than AST in most types of liver disease (i.e., AST/ALT ratio < 1). Elevated AST in relation to ALT (i.e., AST/ALT ratio > 2), along with high GGT, can occur with alcoholic hepatitis. Isolated AST elevation (without ALT elevation) may indicate cardiac or muscle disease.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.