Liver function tests (LFT)-
There are 4 different liver enzymes examined during an LFT
Alanine transaminase (ALT)
Aspartate aminotransferase (AST)
Alkaline phosphatase (ALP)
Alanine transaminase (ALT) -
Is found within hepatocytes, therefore this can be a measure of hepatocellular damage
Aspartate aminotransferase (AST) -
Mostly found in the liver, however also found in muscles. When cells are damaged they release AST into the blood stream. High levels in blood could indicate hepatitis, cirrhosis or liver diseases.
Alkaline phosphatase (ALP) -
Found in the liver, bones and bile ducts and therefore can be used as a marker for cholestasis (decrease in bile flow)
Is found throughout the body but mostly within the liver. High levels can be associated with liver disease or damage to bile ducts.
How to interpret the different enzymes-
ALT > AST is associated with chronic liver disease
AST > ALT is associated with cirrhosis and acute alcoholic hepatitis
A greater than 10-fold increase in ALT and a less than 3-fold increase in ALP suggests a predominantly hepatocellular injury.
A less than 10-fold increase in ALT and a more than 3-fold increase in ALP suggests cholestasis.