Antioxidants and Biomarkers of Oxidative Stress in Preterm Infants with Symptomatic Patent Ductus Arteriosus

Objective Immature antioxidant and oxygen-sensing mechanisms are involved in the pathogenesis of the patent ductus arteriosus (PDA). We conducted a prospective, observational, pilot study to test the hypothesis that antioxidant activity is low at birth in preterm infants at risk for symptomatic PDA. Study Design Blood and urine samples were collected within 24 to 48 hours of life in 53 preterm infants (32 weeks' gestation) who developed early PDA symptoms and in 30 term (37 weeks' gestation) control infants. Thirty preterm infants developed hemodynamically significant PDA (hsPDA) and required pharmacologic treatment and/or PDA ligation. For these infants, blood and urine samples were also collected at 24 hours posttreatment. Samples were analyzed for biomarkers of antioxidant activity, oxidative stress, and lipid peroxidation. Results At 24 to 48 hours after birth, plasma superoxide dismutase (SOD), urinary catalase, and plasma and urinary 8-isoPGF(2 alpha) were significantly lower in preterm infants who developed hsPDA. Plasma 8-isoPGF(2 alpha) levels rebounded post-PDA treatment, while urinary prostaglandin E-2, plasma and urinary thromboxane B-2, and plasma SOD declined. Conclusion The antioxidant status is low in preterm infants at risk for developing hsPDA. SOD may be a key antioxidant regulating functional ductus arteriosus closure. Therefore, low levels may result in persistence of a hsPDA.