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Key Features

Essentials of Diagnosis

  • Acute hepatitis with deepening jaundice

  • Extreme elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT)

  • Prolonged prothrombin time (PT) and international normalized ratio (INR)

  • Encephalopathy and cerebral edema

  • Asterixis and fetor hepaticus

General Considerations

  • Defined as acute liver dysfunction associated with significant hepatic synthetic dysfunction evidenced by vitamin K–resistant coagulopathy (INR > 2.0) within 8 weeks of onset of liver injury

  • Common causes

    • Neonates: herpesviruses and enteroviruses, neonatal iron storage disease, galactosemia, fructosemia, tyrosinemia, fatty acid oxidation defects, mitochondrial disorders, congenital heart disease

    • Infants 1–24 months: hepatitis A virus, hepatitis B virus, fatty acid oxidation defects, mitochondrial disorders, tyrosinemia, fructosemia, bile acid synthesis defects, acetaminophen, valproate, autoimmune hepatitis, hemophagocytic lymphohistiocytosis

    • Children: Epstein-Barr virus, hepatitis A virus, fatty acid oxidation defects, Wilson disease, acetaminophen, valproate, autoimmune hepatitis

    • Adolescents: Epstein-Barr virus, hepatitis A virus, fatty acid oxidation defects, Wilson disease, acute fatty liver of pregnancy, acetaminophen, valproate, herbs, "ecstasy," autoimmune hepatitis

Clinical Findings

Symptoms and Signs

  • Children may present with flu-like symptoms, including malaise, myalgias, jaundice, nausea, and vomiting

  • Jaundice, fever, anorexia, vomiting, and abdominal pain are most common

  • Tender hepatomegaly may be followed by progressive shrinking of the liver, often with worsening hepatic function

  • Signs of chronic liver disease (splenomegaly, spider hemangiomata) should suggest an underlying chronic liver disease

  • Hyperreflexia and positive extensor plantar responses are seen before the onset of encephalopathy

  • In some patients, presents with rapid development of deepening jaundice, bleeding, confusion, and progressive coma, while others are asymptomatic at the onset and then suddenly become severely ill during the second week of the disease

  • A careful history of drug and toxin exposure may identify a drug-induced cause

Differential Diagnosis

  • Severe hepatitis, with or without coagulopathy, due to infections, metabolic disease, autoimmune hepatitis, or drug toxicity can initially mimic ALF

  • Acute leukemia, cardiomyopathy, and Budd-Chiari syndrome can mimic severe hepatitis

  • Patients with Reye syndrome or urea cycle defects are typically anicteric


Laboratory Findings

  • Characteristic findings

    • Elevated serum bilirubin levels (usually > 15–20 mg/dL)

    • Sustained elevations of AST and ALT (> 3000 units/L)

    • Low serum albumin

    • Hypoglycemia

    • Prolonged PT and INR

  • Blood ammonia levels become elevated, whereas blood urea nitrogen is often very low

  • A high AST and ALT with normal bilirubin suggests acetaminophen toxicity or metabolic causes


  • Excellent critical care is paramount, including careful management of hypoglycemia, bleeding and coagulopathy, hyperammonemia, cerebral edema, and fluid balance, while systematically investigating for potentially treatable causes

  • Acyclovir is essential in herpes simplex or varicella-zoster virus infection.

  • For hyperammonemia, oral antibiotics such as neomycin or rifaximin, and lactulose (1–2 mL/kg three or four times daily) are used to reduce blood ammonia levels and trap ammonia in ...

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