Hepatic encephalopathy

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  • Diagnosis of exclusion
  • Due to accumulation of nitrogenous waste products normally metabolized by the liver
  • Increased metabolism of ammonia to glutamine in CNS
  • Spectrum of illness ranges from chronic fatigue to acute lethargy


  • Increased ammonia production, absorption or entry into brain:
  • Dehydration
  • Drugs
    • Opioids
    • Benzodiazepines (including withdrawal)
    • ETOH (including withdrawal)

Clinical Features


  • Stage I - General apathy
  • Stage II - Lethargy, drowsiness, variable orientation, asterixis
  • Stage III - Stupor with hyperreflexia, marked disorientation, inability to follow commands, extensor plantar reflexes
  • Stage IV - Coma

Differential Diagnosis



  • CBC
  • Chemistry
  • Ammonia level
  • LFTs
  • PT/PTT
  • Urinalysis
  • CXR
  • Head CT
  • Paracentesis in patient with ascites (rule out SBP)
  • Consider LP


  • Elevated ammonia level
  • History of any new medications or toxin ingestion
  • Focus exam on looking for signs of GI bleed or hypovolemia


  • Lactulose 20g PO or (300mL in 700cc H2O retention enema x30min)
    • In colon degrades into lactic acid: acidic environment traps ammonia
    • Also inhibits ammonia production in gut wall


  • Discharge stage I or II with known ecephalopathy and who is otherwise well

Patient Information

Hepatic Encephalopathy (Medline Plus)

See Also