GPT and animal viral hepatitis: Diagnosis of DILI incorporates measurements of these enzymes based on Hy’s Law, where if ALT is ≥ 3 × the upper limit of normal (ULN) and TBL is ≥ 2 × ULN and there is no other likely cause of enzyme elevations such as viral hepatitis then DILI can be assumed (Hornby et al. 2014; Kullak-Ublick et al. 2017).