Is a blood ammonia level of 63 micromoles per liter considered hyperammonemia?

From the Guidelines

An ammonia level of 63 is indeed considered high and requires immediate medical attention. According to the consensus guidelines for management of hyperammonaemia in paediatric patients receiving continuous kidney replacement therapy 1, typically, blood ammonia concentrations ≤35 µmol/l (<60 µg/dl) are considered normal.

Key Points to Consider

• High concentrations of ammonia can produce toxic effects and levels >200 µmol/l (341 µg/dl) are associated with poor neurological outcomes 1.
• The primary differential diagnosis of hyperammonaemia in infants and children relates to inborn errors of metabolism, including urea cycle disorders (UCDs) and organic acidaemias 1.
• Toxic levels of ammonia can be due to either a primary or a secondary deficiency of the urea cycle, and can also occur in the context of other congenital metabolic abnormalities, following exposure to certain drugs, and in various liver diseases 1.

Clinical Implications

• High ammonia levels are concerning because ammonia is neurotoxic and can lead to confusion, lethargy, and in severe cases, encephalopathy or coma.
• Treatment depends on the underlying cause but may include medications to reduce ammonia production in the gut, dietary protein restriction, and addressing the primary condition.
• Anyone with elevated ammonia levels should be evaluated by a healthcare provider promptly, especially if experiencing neurological symptoms, as untreated hyperammonemia can lead to serious complications.

From the Research

Ammonia Levels

• The provided studies do not specify a normal or high range for ammonia levels, but they do discuss the clinical impact of hyperammonemia in patients with liver disease 2, 3.
• Elevated arterial ammonia levels are associated with high mortality in patients with acute liver failure (ALF) and hypoxic hepatitis (HH) 2.
• Peak arterial ammonia levels differed significantly between transplant-free 28-day survivors and non-survivors in the HH and ALF groups 2.
• Admission arterial ammonia levels were independently linked to hepatic encephalopathy grades 3/4 in patients with HH, ALF, and cirrhosis 2.
• Serum ammonia levels have prognostic value and have been implicated in sarcopenia, hepatotoxicity, and immune dysfunction in cirrhosis 3.

Clinical Utility of Ammonia Testing

• The clinical utility of serum ammonia levels has been questioned, citing challenges in accurate measurement and interpretation 4, 3.
• Serum ammonia testing has not had consistent benefit in clinical diagnosis or management of HE in cirrhosis 3.
• Claims data indicated that ammonia testing increased substantially during the study period, particularly after the advent of electronic medical record systems 3.

Specific Ammonia Level of 63

• There is no direct information in the provided studies to determine if an ammonia level of 63 is considered high 4, 5, 6, 2, 3.
• The studies suggest that elevated ammonia levels are associated with poor prognosis and advanced HE in patients with liver disease, but do not provide a specific threshold for what is considered a high ammonia level 2, 3.