From the Guidelines
An ammonia level of 94 is significantly elevated and requires immediate medical attention, with management focusing on lowering ammonia levels while treating the underlying cause, typically through the administration of nitrogen-scavenging agents and urea cycle intermediates as recommended in the consensus guidelines for management of hyperammonaemia in paediatric patients receiving continuous kidney replacement therapy 1. The management should prioritize the use of intravenous sodium benzoate and sodium phenylacetate, given over 90 min as bolus then as maintenance over 24 h, with dosages based on body weight, as well as intravenous l-arginine hydrochloride and l-carnitine, to aid in ammonia removal and prevent further accumulation. Key considerations include:
- Discontinuing all oral feeds and providing adequate calories (≥100 kcal/kg daily) as intravenous glucose and lipids, with a glucose infusion rate of 8–10 mg/kg/min and lipids (0.5 g/kg daily, up to 3 g/kg daily) 1.
- Maintaining a glucose infusion rate of 8–10 mg/kg/min and providing lipids (0.5 g/kg daily, up to 3 g/kg daily) to prevent catabolism and promote anabolism 1.
- Using nitrogen-scavenging agents, such as sodium benzoate and sodium phenylacetate, at the recommended dosages, and urea cycle intermediates, such as l-arginine and l-citrulline, to aid in ammonia removal 1.
- Considering continuous kidney replacement therapy (CKRT) or haemodialysis (HD) in patients with severe hyperammonaemia, with CKRT being the recommended first-line treatment when possible, and HD being recommended in patients who require rapid ammonia clearance 1. Regular monitoring of ammonia levels, mental status, and vital signs is essential during treatment, with adjustments made as necessary to prevent rebound hyperammonaemia and ensure optimal patient outcomes.
From the FDA Drug Label
Lactulose causes a decrease in blood ammonia concentration and reduces the degree of portal-systemic encephalopathy. Controlled studies have shown that lactulose solution therapy reduces the blood ammonia levels by 25 to 50%; The patient with an ammonia level of 94 should be managed with lactulose (PO) as it has been shown to decrease blood ammonia concentration and reduce the degree of portal-systemic encephalopathy 2, 2.
- The goal of treatment is to reduce the blood ammonia levels, which can be achieved with lactulose therapy.
- Lactulose has been shown to reduce blood ammonia levels by 25 to 50% in controlled studies 2.
From the Research
Management of Hyperammonemia
To manage an ammonia level of 94, several treatment options can be considered:
- Administration of intravenous calories as glucose and lipids to promote anabolism, as well as carnitine to promote urinary excretion of organic acid esters 3
- Correction of metabolic acidosis with the substitution of bicarbonate for chloride in intravenous fluids 3
- Use of ammonia scavengers such as sodium benzoate or sodium phenylbutyrate 3, 4
- Treatment with N-carbamyl-L-glutamate to rapidly normalize ammonia levels by stimulating the first step of the urea cycle 3
- Detoxification of ammonia using extracorporeal means such as haemodialysis 5
- Long-term management with a low-protein diet and the use of nitrogen scavengers 5
Treatment Strategies
Different treatment strategies may be employed depending on the underlying cause of hyperammonemia:
- For symptomatic hyperammonemia following asparaginase therapy, sodium benzoate may be used as a first-line ammonia scavenger 4
- For primary hyperammonaemia, treatment may involve a combination of detoxification, intravenous drugs, and long-term management with a low-protein diet and nitrogen scavengers 5
- For hepatic encephalopathy, lactulose and rifaximin may be used as measures for secondary prophylaxis 6