R Factor
( ALT / upper limit of normal ALT ) / ( Alkaline Phosphatase / upper limit of normal Alkaline Phosphatase )
The R Factor helps to determine the cause of abnormal liver enzyme testing to be either hepatocellular or cholestatic
The R Factor if < 2 suggests cholestatic injury. An R Factor between 2 and 5 may be a mixed cholestatic/hepatocellular injury. An R Factor > 5 suggests hepatocellular injury