Acute Liver Failure and Encephalopathy in a 5-Year-Old
A 5-year-old boy is brought to the emergency department with confusion and jaundice. He had a mild upper respiratory infection 2 weeks ago and was given acetaminophen for fever. His mother reports that he has been increasingly sleepy and disoriented over the past 2 days. On exam, he is jaundiced, has asterixis, and hepatomegaly with tenderness. Vital signs: HR 120, BP 90/50, RR 30, Temp 37.5°C. Laboratory tests: ALT 4500 U/L, AST 5200 U/L, total bilirubin 15 mg/dL, direct bilirubin 10 mg/dL, INR 3.5, ammonia 150 µmol/L, glucose 45 mg/dL. Acetaminophen level is undetectable. Viral serologies are pending. Ultrasound shows a patent portal vein and no ascites.
1. What is the most likely cause of acute liver failure in this child, and what immediate management is required?
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The most likely cause is acute liver failure due to a viral infection (e.g., hepatitis A, B, or herpes simplex) or drug-induced liver injury (though acetaminophen level is undetectable, a history of therapeutic dosing may still be causative if other factors). Other causes include autoimmune hepatitis or metabolic disorders. Immediate management includes stabilization (airway, breathing, circulation), correction of hypoglycemia with IV dextrose, management of coagulopathy (vitamin K, FFP if bleeding), and treatment of encephalopathy (lactulose, rifaximin). N-acetylcysteine should be given even if acetaminophen level is undetectable, as it may be beneficial in non-acetaminophen acute liver failure. Transfer to a pediatric liver transplant center is critical. Intracranial pressure monitoring may be needed. The prognosis depends on the cause and the rapidity of intervention.
2. What are the criteria for listing for liver transplantation in pediatric acute liver failure?
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The criteria for listing for liver transplantation in pediatric acute liver failure include INR > 2.0 (or >1.5 with encephalopathy), persistent hypoglycemia, rising bilirubin, encephalopathy grade III or IV, and multiorgan failure. The Pediatric End-Stage Liver Disease (PELD) score is used for children under 12, but in acute liver failure, the decision is often based on clinical trajectory. The King's College criteria are used for acetaminophen-induced and non-acetaminophen-induced liver failure, but pediatric-specific criteria are less standardized. The presence of cerebral edema and high ammonia (>150-200 µmol/L) are poor prognostic signs. Early referral to a transplant center is essential. The family should be counseled about the possibility of transplantation and the need for immediate evaluation.