In a child with acute liver failure, the most impoant abnormal serum biochemical test that indicates poor prognosis:

Definition of Acute liver failure in children includes: Biochemical evidence of acute liver injury (usually <8 wk duration); No evidence of chronic liver disease; Hepatic-based coagulopathy defined as i) a prothrombin time (PT) >15 sec or international normalized ratio (INR) >1.5 not corrected by vitamin K in the presence of clinical hepatic encephalopathy, or ii) a PT >20 sec or INR >2 regardless of the presence of clinical hepatic encephalopathy. Hepatic synthetic function is reflected in serum albumin and protein levels and in the PT or INR Unresponsiveness of PT to vitamin K suggests severe hepatic disease Serum aminotransferase activities do not correlate well with the severity of the illness.