What is acute liver failure, and how is it defined?

Acute liver failure (ALF) is a life-threatening condition in a patient with no pre-existing liver disease, defined by the triad of liver injury (abnormal liver tests), coagulopathy (INR greater than 1.5), and hepatic encephalopathy.

Clinical relevance. Recognising the defining triad in a previously healthy liver prompts urgent specialist referral.

More Detail

Acute liver failure

ALF is the rapid loss of liver function in a previously healthy liver, a rare but often fatal emergency.

Definition (the triad)

• Liver injury: abnormal liver tests (markedly raised aminotransferases).
• Coagulopathy: INR greater than 1.5 (impaired synthesis of clotting factors).
• Hepatic encephalopathy.

Key qualifier

• Occurs in a patient with no pre-existing chronic liver disease - this distinguishes it from decompensated cirrhosis (although exceptions exist, e.g. Wilson's disease, Budd-Chiari, delta superinfection presenting as ALF).

Why it matters

• It can progress rapidly to multi-organ failure and death; early recognition and transfer to a specialist/transplant unit are critical.