Plasma ammonia concentrations in newborns and children.
Many, mostly congenital, hyperammonemic syndromes may occur in the first days of life. For the diagnosis of these disorders plasma ammonia levels physiologically present in neonates and early childhood should be known, preferably by the use of an enzymatic method. Full-term newborns had higher capillary ammonia concentrations on the first day of life (30-144 mumol/l) than on the fifth day (31-104 mumol/l). In the same individuals the arterial (38-89 mumol/l) are lower than the capillary concentrations (69-112 mumol/l). The venous concentrations in school children were not higher than in adults. The scatter of capillary values, however, is great. For diagnostic purposes of disorders of ammonia detoxication sampling of arterial or venous blood is preferable.