Hepatic encephalopathy

Background

• 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

Precipitants

• Increased ammonia production, absorption or entry into brain:
  • GI Bleed
  • Excess dietary intake of protein
  • Infection (e.g. SBP)
  • Hypokalemia
  • Metabolic Alkalosis
  • Constipation
• Dehydration
  • Vomiting
  • Diuretics
• Drugs
  • Opioids
  • Benzodiazepines (including withdrawal)
  • ETOH (including withdrawal)

Clinical Features

Stages

• 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

• Subdural Hematoma
• Hypoglycemia
• Wernicke-Korsakoff Syndrome
• Hyper/hyponatremia
• Benzodiazepine Overdose (decreased hepatic clearance)
• Renal Failure
• Sepsis

Evaluation

Workup

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

Evaluation

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

Management

• 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

Disposition

• Discharge stage I if good resources.
• Stage II will need admission unless known encephalopathy and who is otherwise well.
• Stage III and IV admission +/- ICU or obs bed.

Patient Information

Hepatic Encephalopathy (Medline Plus)

See Also

• Acute hepatic failure