Urea Cycle Defects: A Challenge for Neonatologists in Limited Resource Settings

Urea cycle defects (UCD)are rare inborn errors of nitrogen detoxification/arginine synthesis. We described clinical course of male newborn, second in order, with enormous concentration of ammonia, 4000 μmol/l. The first child died in early neonatal period with diagnosis of “severe neonatal sepsis”. Laboratory finding showed no metabolic acidosis, abnormal plasma amino acids, absence of citrulline and increased urinary orotic acid. Despite aggressive treatment including he modyafiltration, hydration with dextrose and salt, dietary regime without proteins, ammonia scavengers as sodium benzoate and arginine repletion, newborn developed severe encephalopathy, multiorgan failure and died on the sixth day following birth. Due to short and catastrophic course of UCD in neonatal period, there is a high possibility of misdiagnosis, especially differential to neonatal sepsis and prompt ammonia measurement is the crucial step. Identifying specific UCD is not available in many countries with limited resources. Laboratory parameters will guide the diagnostic workup of a patient with hyperammonemia for which a specific diagnosis is yet unclear. Since the molecular genetic testing is the method of first choice, in order to confirm the diagnosis it is necessary to preserve frozen fibroblasts and provide genetic counseling.