Ammonia (NH3)

Special Precautions/Comments:

Always contact the laboratory before taking a sample. 

Sample very unstable, please transport immediately to laboratory (ideally on ice) for analysis within 30 minutes of taking the sample. Failure to do so can result in falsely elevated results.  

Guidelines for undiagnosed hyperammonaemia (British Inherited Metabolic Disease Group)

Additional Information:

Ammonia (NH3) is a by-product of protein metabolism which is converted to urea by the liver for renal excretion. Ammonia is toxic and at high levels it can result in neurological symptoms, vomiting and respiratory alkalosis. Ammonia measurement should be performed in patients with acute encephalopathy and in acutely ill neonates.  

High ammonia levels (hyperammonaemia) can be caused by liver disease such as cirrhosis due to decreased conversion of ammonia to urea, renal failure due to reduced clearance of urea, and sepsis. More rarely, hyperammonaemia may result from inherited metabolic disorders such as urea cycle disorders, organic acid disorders and fatty acid oxidation disorders. These inherited metabolic disorders usually present in infancy or childhood. Ammonia levels can be falsely elevated in haemolysis or if analysis is delayed.