Fig. 4: Schematic, initial diagnostic algorithm for a patient presenting with mild aminotransferase abnormality. Fig. 4: Schematic, initial diagnostic algorithm for a patient presenting with mild aminotransferase abnormality. HCV = hepatitis C virus, HBsAG = hepatitis B surface antigen, ANA = antinuclear antibodies, ASMA = anti-smooth body antibodies, LKM = liver–kidney microsomes. Alcohol abuse and, to a lesser extent, drug-induced liver injury are frequently associated with mild aminotransferase abnormality, and their causality should be ruled out on a clinical basis. In the western world, chronic viral hepatitis, autoimmune hepatitis and hereditary hemochromatosis are the most common causes of mild aminotransferase alteration for which specific serological tests are available. Although nonalcoholic fatty liver disease (NAFLD) or steatohepatitis is frequently encountered in clinical practice, it remains a diagnosis of exclusion. Edoardo G. Giannini et al. CMAJ 2005;172:367-379 ©2005 by Canadian Medical Association