Reye Syndrome



  • Reversible clinicopathologic syndrome of unknown etiology
  • Primary mitochondrial injury
  • Decreased enzyme activity:
    • Krebs cycle
    • Gluconeogenesis
    • Urea biosynthesis
  • Fatty infiltration:
    • Liver:
      • Hyperammonemia due to decreased conversion from ammonia to urea
      • Hepatorenal syndrome may be the end result
      • Rapid recovery of liver function in survivors
    • Brain:
      • Encephalopathy of unclear etiology
      • Cytotoxic edema
      • Deteriorating level of consciousness reflects increasing intracranial pressure (ICP)
      • Herniation is the most common cause of death
      • Normal recovery of neurologic function in survivors
    • Skeletal and myocardial muscle
    • Fatty infiltration and distorted mitochondria
  • <10% of cases occur before the age of 1 yr:
    • Average age is 7 yr
    • Peak age is 4–11 yr
    • Extremely rare in age >18 yr
  • Regional differences:
    • Highest incidence in the Midwestern states
    • Lower incidence in the states of the Southeast and far West
  • More common in whites than in blacks
  • Peak incidence in winter and early spring
  • Reye-like syndrome:
    • Describes conditions resulting in defects in urea and fatty acid metabolism, toxicologic injury, and impaired gluconeogenesis


  • Not known with certainty
  • Multifactorial causes have been epidemiologically implicated:
    • Antecedent viral syndrome
    • Influenza A or B
    • Varicella
    • Diarrhea illness
    • Genetic predisposition
    • Exposure to salicylates
    • Other undefined factors

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