What is the treatment for hyperammonemia (elevated ammonia level)?

Treatment of Hyperammonemia with Ammonia Level of 209

For an ammonia level of 209 μmol/L, immediate treatment should include nitrogen scavenger medications, temporary protein restriction, and intravenous glucose supplementation, with consideration for hemodialysis if clinical deterioration occurs. 1, 2

Initial Management

• Stop protein intake temporarily to prevent further ammonia production 1, 2
• Administer intravenous glucose at 8-10 mg/kg/min to prevent catabolism 1
• Provide intravenous lipids (0.5 g/kg daily, up to 3 g/kg daily) for caloric support 1
• Aim for caloric intake ≥100 kcal/kg daily to prevent protein breakdown 1

Pharmacological Treatment

• Administer nitrogen-scavenging agents as your ammonia level exceeds 150 μmol/L (255 μg/dl) 1, 2:

  • Intravenous sodium benzoate (loading dose over 90 min followed by maintenance over 24h):
    • If weight <20 kg: 250 mg/kg
    • If weight >20 kg: 5.5 g/m² 1, 3
  • Intravenous sodium phenylacetate (same dosing as sodium benzoate) 1, 3
  • These medications provide alternative pathways for nitrogen excretion 3

• For patients with suspected urea cycle disorders, add L-arginine hydrochloride:

  • For OTC and CPS deficiencies:
    • Weight <20 kg: 200 mg/kg
    • Weight >20 kg: 4 g/m² 1, 3
  • For ASS and ASL deficiencies:
    • Weight <20 kg: 600 mg/kg
    • Weight >20 kg: 12 g/m² 1, 3

Monitoring

• Measure ammonia levels frequently to assess treatment response 3
• Monitor neurological status for signs of encephalopathy 2
• Check electrolytes, blood gases, liver enzymes, and plasma amino acids 3
• Watch for signs of cerebral edema which may require additional interventions 2

Indications for Dialysis

• Your current ammonia level of 209 μmol/L does not immediately require dialysis, but monitor closely 1, 2
• Consider hemodialysis if:
  • Neurological status rapidly deteriorates 1
  • Ammonia levels rise above 300-400 μmol/L despite medical therapy 1
  • Signs of moderate to severe encephalopathy develop 1

Dialysis Options (if needed)

• Hemodialysis (HD) is most effective with 95-96% ammonia filtration fraction 1
• Continuous kidney replacement therapy (CKRT), specifically high-dose CVVHD, is recommended as first-line if available 1
• Peritoneal dialysis should only be used if other KRT modalities are unavailable 1

Reintroduction of Protein

• Reintroduce protein within 48 hours after ammonia levels decrease to 80-100 μmol/L to prevent catabolism 1
• Gradual reintroduction with careful monitoring of ammonia levels 2

Potential Pitfalls

• Delayed recognition and treatment can lead to irreversible neurological damage 2, 4
• Ensure proper collection and processing of ammonia samples to avoid false elevations 2
• Avoid prolonged protein restriction beyond 48 hours 1
• Be aware that nitrogen scavengers will be dialyzed along with ammonia during KRT but can still be effective 2, 3

Special Considerations

• If hyperammonemia is due to a urea cycle disorder, long-term management will be needed 4, 5
• In patients with liver disease, ammonia levels may not correlate with encephalopathy severity, so treat based on clinical presentation as well 6
• Consider unusual causes of hyperammonemia if liver function is normal (medications like valproic acid, hematologic malignancies) 7