Acute Liver Failure
Massive hepatocyte necrosis in a liver with no pre-existing disease strips out clotting-factor synthesis and ammonia clearance, so coagulopathy and encephalopathy appear together within days to weeks.
Definition
Acute liver failure is a coagulopathy of hepatic origin together with hepatic encephalopathy of any grade, arising in a person with no pre-existing liver disease. It is a syndrome with many causes rather than a diagnosis in itself, and the cause changes both the treatment and the prognosis.
First principles
Coagulopathy plus encephalopathy is the diagnosis, not a high ALT
Look for acute liver failure in anyone without pre-existing cirrhosis whose INR reaches 1.5 or above, in an illness of 26 weeks or less. Hepatic encephalopathy in that setting is what turns liver injury into liver failure. Early grades are subtle, so look for them deliberately. Ammonia and serial lactate help when the cause of confusion is not obvious.
This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.