Serum Aminotransferases
- AST - in decreasing order of concentration, found in the following:
liver, cardiac muscle, skeletal muscle, kidneys, brain, pancreas, lungs, leukocytes/erythrocytes
-ALT - found primarily in the liver
Pattern of aminotransferase elevation can be helpful
ALT ≥ AST in most acute hepatocellular disorders
AST:ALT ratio > 2:1 suggestive of alcoholic liver disease (AST: ALT ratio > 3:1 highly suggestive)
AST rarely > 300 U/L in alcoholic liver disease(ALT often normal)
serum ALT low in alcoholic liver disease due to deficiency of pyridoxal phosphate
-Absolute elevations of aminotransferases - no prognostic significance in acute hepatocellular disorders
-Any type of liver cell injury
modest elevations in serum aminotransferases
levels up to 300 U/L -nonspecific
Obstructive jaundice
serum aminotransferases usually NOT greatly elevated
exception - during acute phase of biliary obstruction (passage of gallstone into common bile duct), can be briefly 1,000-2,000 U/L then quickly decrease and evolve into pattern typical of cholestasis (while stone increased)