Table 1.

Thresholds of ALT and ALP and typical features in patients with liver adaptation and liver injury.

Description	Thresholds of Liver Tests	Criteria and Characteristic Features
Liver adaptation	ALT ≤ 5 times of ULN and/or ALP ≤ 2 times of ULN	● Develops at low doses of a drug ● Presumably the majority of drugs have the potency of causing rare but clinically not apparent liver adaptation ● No signs of liver injury in histology ● Normalization or stabilization of liver tests is commonly observed whether the drug use is stopped or continued
Idiosyncratic liver injury	ALT ≥ 5 times of ULN and/or ALP ≥ 2 times of ULN	● Develops at low doses of a drug ● Signs of liver injury found in histology ● Cessation of drug use is mandatory and immediate ● Worsening if drug use is continued ● Most drugs cause idiosyncratic DILI ● Risk of acute liver failure
Intrinsic liver injury	ALT ≥ 5 times of ULN and/or ALP ≥ 2 times of ULN	● Develops with overdosed drugs ● Signs of liver injury found in histology ● Cessation of drug use is mandatory and immediate ● Caused by a few drugs ● Risk of acute liver failure