GPT and thromboangiitis obliterans: In another study, although the indirect Coombs test was positive in 70% of the TAO patients with high levels of LDH (Lactate dehydrogenase) and AST (Aspartate aminotransferase) and normal levels of ALT (Alanine aminotransferase), the definitive diagnosis of hemolytic anaemia was not confirmed, because of the normal level of bilirubin as well as the normal or high level of haptoglobin [10].