GPT and cholestasis: Increased serum ALP has been proposed as a biomarker for cholestasis, hepatic microsomal enzyme induction, peroxisomal proliferation, and hepatocellular hypertrophy, with no evidence as a marker for necrosis, whereas serum ALT and AST are biomarkers of hepatocellular injury (Ennulat et al. 2010; Hall et al. 2012; Pollock and Minuk 2017).