Test Details: Ammonia is a waste product of protein catabolism; which is potentially toxic to the central nervous system. Increased plasma ammonia can be indicative of hepatic encephalopathy, hepatic coma in terminal stages of liver cirrhosis, hepatic failure, acute and subacute liver necrosis and Reye's syndrome. This test assists in the diagnosis of hepatic coma and in investigation and monitoring treatment of inborn errors of metabolism. This test is also used for evaluating patients with advanced liver disease.