How do you treat hyperammonemia with an ammonia level of 132?

Treatment of Hyperammonemia with Ammonia Level of 132

For an ammonia level of 132 μmol/L, immediate treatment should include temporary protein restriction, intravenous glucose and lipid supplementation, and consideration of nitrogen scavenger medications if the level rises above 150 μmol/L. 1

Initial Management

• Immediately stabilize the patient's circulation, airway, and breathing, with intubation and ventilation if necessary 2, 3
• Establish intravenous access for administration of fluids and medications 3
• Temporarily stop protein intake to reduce nitrogen load and prevent further ammonia production 4, 1
• Provide adequate calories through intravenous glucose and lipids to prevent catabolism:
  • Administer intravenous glucose at 8-10 mg/kg/min 1, 5
  • Provide intravenous lipids (0.5 g/kg/day, up to 3 g/kg/day) 4, 1
  • Aim for caloric intake ≥100 kcal/kg/day 4, 1
• Monitor plasma ammonia levels every 3-4 hours until normalized 4, 1

Pharmacological Management

• At the current level of 132 μmol/L, pharmacological therapy with nitrogen scavengers is not yet indicated, as they are generally started at levels >150 μmol/L 1
• If ammonia levels rise above 150 μmol/L, initiate nitrogen scavengers such as sodium benzoate and sodium phenylacetate 1, 5:
  • For patients <20 kg: sodium benzoate and sodium phenylacetate at 250 mg/kg as loading dose over 90-120 minutes, followed by the same dose as maintenance over 24 hours 5
  • For patients >20 kg: sodium benzoate and sodium phenylacetate at 5.5 g/m² as loading dose over 90-120 minutes, followed by the same dose as maintenance over 24 hours 5
• For patients with suspected urea cycle disorders, add L-arginine hydrochloride based on the specific enzyme deficiency 5

Monitoring During Treatment

• Check plasma ammonia levels every 3-4 hours until normalization 4, 1
• Monitor electrolytes, blood glucose, venous or arterial blood gases, AST, and ALT 5
• Assess neurological status regularly for signs of encephalopathy 3, 1
• Watch for early symptoms of worsening hyperammonemia including lethargy, somnolence, and disorientation 1, 6

Indications for Dialysis

• At the current level of 132 μmol/L, dialysis is not yet indicated 2, 1
• Consider hemodialysis if:
  • Ammonia levels rise above 300-400 μmol/L despite medical therapy 4, 1
  • Neurological status rapidly deteriorates 1, 7
  • Signs of moderate to severe encephalopathy develop 4, 1
• Hemodialysis is the most effective method for rapidly reducing blood ammonia levels, with 95-96% ammonia filtration fraction 1, 7
• For hemodynamically unstable patients, continuous kidney replacement therapy (CKRT), specifically high-dose continuous venovenous hemodialysis (CVVHD), is recommended 4, 1

Reintroduction of Protein

• Reintroduce protein within 48 hours after ammonia levels decrease to 80-100 μmol/L to prevent catabolism 2, 1
• Start with 0.25 g/kg/day and gradually increase up to 1.5 g/kg/day as tolerated 4, 1
• Avoid prolonged protein restriction beyond 48 hours to prevent catabolism 4, 1

Common Pitfalls and Caveats

• Delayed recognition and treatment can lead to irreversible neurological damage 2, 1
• Ammonia samples must be collected from free-flowing venous or arterial blood, transported on ice, and processed within 15 minutes to avoid false elevations 2, 3
• Protein restriction should not be prolonged beyond 48 hours to avoid catabolism 4, 1
• Nitrogen scavengers will be dialyzed along with ammonia during KRT but can still be effective when used concurrently 4, 1
• Duration of hyperammonemic coma >3 days and plasma ammonia levels >1,000 μmol/L are poor prognostic factors 2, 1