Measurement of ammonia in blood

The measurement of ammonia, now known to be a normal constituent of all bod y fluids, is fraught with problems. An elevated ammonia level in blood (100 mu mol/L or higher) is an indicator of an abnormality in nitrogen homeosta sis. The collection, handling, storage, and analysis of blood samples, thei r limitations, and potential sources of error are discussed. New techniques that permit continuous or real-time estimates of systemic ammonia levels o ver a broad range are also discussed. The aim should always be to minimize the release of ammonia from the collected sample before analysis. Recommend ations are made on the collection and processing of blood samples, for it i s by standardization and rigid adherence to these techniques that the relia bility of the test results will be improved.