<prompt> In a child with acute liver failure, the most impoant abnormal serum biochemical test that indicates poor prognosis:Increasing transaminasesIncreasing bilirubinIncreasing prothrombin timeReversal of serum albumin-globulin ratio  <response>: 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. 