Ammonia is one of the by-products of protein metabolism. Elevated blood ammonia levels have been associated with severe liver dysfunction such as hepatic encephalopathy, coma resulting from cirrhosis, severe hepatitis, Reye's syndrome, and drug hepatotoxicity. Also, elevated blood ammonia has been reported in cardiac failure, azotemia, and pulmonary emphysema. Correlation between plasma ammonia and the degree of encephalopathy can be erratic.
Patient should not clench fist during collection, as muscular exertion often increases venous ammonia levels. Patient should avoid smoking prior to phlebotomy since smoking increases plasma ammonia levels. Phlebotomist should not use a tourniquet when collecting sample. Estimated turnaround for results is 3 business days. If confirmation testing is required, the estimated time may be extended.