Pediatria pre prax 6/2019
Hyperammonemia
Hyperammonemia is characterized by an excess of ammonia in the blood. It is caused by diverse group of disorders. Most severe of them are due to defects in urea cycle enzymes or transporters. Because of secondary inhibition of urea cycle several other inherited metabolic disorders such as certain organic acidurias, fatty acid oxidation disorders, mitochondrial disorders can also lead to hyperammonemia. Acquired causes of hyperammonemia include liver dysfunction, certain drugs, intestinal bacterial overgrowth, transient hyperammonemia of the newborns, provision of total parenteral nutrition etc. Plasma ammonia is the first and most important test for the diagnosis of hyperammonemia. Plasma and urine amino acids, organic acids in urine and acylcarnitines in dry blood spot are used as biomarkers in the differential diagnosis of hyperammonemia. These investigations and many other routine laboratory tests are needed in the diagnosis, treatment, and follow-up of patients with hyperammonemia.
Keywords: hyperammonemia, urea cycle disorders, preanalytic factors of ammonia measuring
