GPT and steatosis: Currently, there is no clear biological mechanism but as well as a marker of CVD risk, AST/ALT ratio stratifies severity of liver disease, and this is independent of features of the metabolic syndrome.25 Moreover, emerging evidence in NAFLD suggests that liver fibrosis (with AST/ALT ratio as a proxy marker) stratifies future CVD risk rather than steatosis alone.12, 14, 18