A study from Liaw et al reported that subclinical and asymptomatic liver injury can be commonly induced by PTU.[42] Tamagno revealed that PTU treatment has a higher risk of hepatotoxicity than MMI.[43] According to the results from the report of Russo et al, PTU ranked the third leading cause of drug-induced liver failure requiring transplants with 23 cases receiving liver transplants between 1990 and 2007 in the United States.[44] This may be because PTU can lead to active metabolites, resulting in the injury of the hepatocellular and the increase of ALT in serum. Here, GPT is linked to liver failure.