Acute autoimmune hepatitis: Many open questions

Autoimmune hepatitis (AIH) is more variable than other liver diseases. Autoimmune hepatitis can present in young infants [1] and in octogenarians [2]. AIH can be a slowly progressive smouldering condition, or it can run an acute fluctuating course characterized by flares and spontaneous apparent remission, albeit usually associated with scarring and progressive fibrosis. AIH can present as a subclinical condition diagnosed on routine blood tests in an asymptomatic person, and it can present as acute liver failure [3]. It is the acute and hyper-acute presentation of AIH that remains the greatest challenge in this disease and at the same time has the least evidence basis to guide diagnosis and management. Key issues are the definition of diagnostic criteria, the need for prognostic parameters, and the therapeutic approach to acute AIH. The report by the King’s College group in this issue of the Journal [4] summarizing their experience in a series of 32 patients with acute severe AIH is thus an important attempt to answer some of these questions. This study only looks at patients with a severe impairment of liver function using an international normalized ratio (INR) of >1.5 as their cut-off, a limit also used as the cut-off for acute liver failure in the large American Acute Liver Failure (ALF) study group [5]. This definition is helpful to allow some comparison between the King’s data and the report of the ALF consortium looking at features of autoimmunity in patients presenting with cryptogenic acute liver failure, and it is the main reason why it was used in the study. This INR definition of liver failure does, however, have an important limitation: patients were included, if at ‘‘any time during the index presentation’’ their INR was >1.5. As jaundice leads to vitamin K deficiency through lack of resorption of this fat-soluble vitamin, substitution of vitamin K is the first measure undertaken in any patient with jaundice and elevated INR, and only those patients remaining above a limit of 1.5 can truly be considered to suffer from liver failure. On the other hand, many patients with very severe acute AIH may still have sufficient hepatic reserve to provide adequate levels of coagulation factors despite severe hepatic inflammation