GPT and liver disorder: Unfortunately, while markers of injury in other organs, such as heart and kidney, seem to be constantly evolving, aside from the introduction of GGT as a marker of liver disease in the 1960s (Szczeklik et al. 1961[65]) there has been very little change in biomarkers of liver injury in clinical use since the introduction of AST and ALT, in contrast to biomarkers for other forms of tissue injury including acute myocardial damage (Figure 2(Fig. 2)).