title: Urinary metabolites of oxidative stress and nitric oxide in preterm and term infants.
abstract: BACKGROUND
  Many neonatal diseases have been associated with oxidative stress and altered nitric oxide status.
  
  
  OBJECTIVE
  To determine the effects of clinical interventions on the levels of urinary peroxides, a marker of oxidative stress, and urinary nitrate/nitrites, indices of nitric oxide production and metabolism, in the first 72 h of life in premature infants.
  
  
  METHODS
  A single, spot urine sample was collected from 82 premature and 20 healthy term infants within the first 72 h of life. The peroxide levels were quantified using a fluorometric method, and nitrate/nitrite levels were quantified by chemiluminescence.
  
  
  RESULTS
  Premature infants had a median peroxide level of 10.0 micromol/mmol creatinine (Cr) (interquartile range 4.8-20.0 micromol/mmol Cr). These values were significantly higher than term infants (median 5.0 micromol/mmol Cr, interquartile range 2.7-10.0 micromol/mmol Cr). Urinary nitrate/nitrite levels were not significantly different between preterm (220.5 micromol/mmol Cr, interquartile range 161-287 micromol/mmol Cr) and healthy term infants (244 micromol/mmol Cr, interquartile range 194-316 micromol/mmol Cr). For urinary peroxides, infants on TPN had significantly higher urinary peroxide levels than infants who were not on TPN at the time of urine collection (p = 0.006). Administration of indomethacin was associated with lower levels of urinary nitrate/nitrites (p = 0.0003). Both effects remained significant after controlling for gestational age, degree of respiratory distress and day of urine collection.
  
  
  CONCLUSIONS
  Monitoring the level of both peroxides and nitrate/nitrite may offer added information about the degree of oxidative stress experienced by a newborn but needs to account for clinical and therapeutic interventions.
authors.affiliation: Division of Neonatology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
authors.forename: Christiana R
authors.initials: CR
authors.lastname: Farkouh
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Merrill
authors.forename: Phillip L
authors.initials: PL
authors.lastname: Ballard
authors.forename: Roberta A
authors.initials: RA
authors.lastname: Ballard
authors.forename: Harry
authors.initials: H
authors.lastname: Ischiropoulos
authors.forename: Scott A
authors.initials: SA
authors.lastname: Lorch
mesh_terms: D015415:Biomarkers / Q000652:urine; D005260:Female; D006801:Humans; D007213:Indomethacin / Q000627:therapeutic use; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D009566:Nitrates / Q000652:urine; D009569:Nitric Oxide / Q000378:metabolism / Q000652:urine*; D009573:Nitrites / Q000652:urine; D018384:Oxidative Stress; D010102:Oxygen Inhalation Therapy; D010289:Parenteral Nutrition, Total; D010545:Peroxides / Q000652:urine*; D012121:Respiration, Artificial; D012127:Respiratory Distress Syndrome, Newborn / Q000188:drug therapy / Q000628:therapy; D013048:Specimen Handling / Q000009:adverse effects; D013997:Time Factors
chemical_list: D015415:Biomarkers; D009566:Nitrates; D009573:Nitrites; D010545:Peroxides; D009569:Nitric Oxide; D007213:Indomethacin