Nitric oxide metabolites in the urine of full-term and preterm infants

Background : In newborn full-term and preterm infants the urine nitrites and nitrates (NOx ) were measured, in order to investigate the effects of different pathological conditions (infection, hypoxia) on systemic nitric oxide production. Methods : Urine nitrites and nitrates were determined by means of the Griess reaction, after reduction of nitrates to nitrites with nitrate reductase. Results : The NOx level was higher in preterm (278 nmol/mL) than full-term (176 nmol/mL) infants. Low NOx (115 nmol/mL) levels accompanied generalized infections, while its high contents (650 nmol/mL) was found in cytomegalovirus and one case of Pneumocystis carinii infection. Moderate increase of NOx production was observed in infants with local pulmonary infections and encephalopathies. Conclusion : The results indicate urinary NOx level is lowered in infants with life-threatening generalized infection. A possibility of a rapid test based on newborn urinary NOx level determination is considered.