GLUTATHIONE-PEROXIDASE IS NOT A FUNCTIONAL MARKER OF SELENIUM STATUS IN THE NEONATAL-PERIOD

Background: The antioxidant enzyme glutathione peroxidase is a selenop rotein that, in adults with low selenium intakes, has a strong linear relationship with blood selenium and hence is used as a functional ind icator of selenium status. Our aim was to evaluate glutathione peroxid ase as a functional marker of selenium status in preterm infants. Meth ods: Erythrocyte glutathione peroxidase activity and plasma and erythr ocyte selenium were measured between days 1-5 and then weekly until di scharge in 63 preterm infants with mean +/- standard error birth weigh t and gestation of 1572 +/- 60g and 30.7 +/- 0.3 weeks. A healthy refe rence group of term infants (n = 46) was assessed at day 5 and at 6 we eks. Results: In preterm infants, over the first 3 months, the associa tion of glutathione peroxidase activity with erythrocyte selenium was weak and inconsistent and nonexistent with selenium intake or plasma s elenium. No correlations between any of these indicators were evident for term infants. In preterm infants, plasma and erythrocyte selenium declined over the first 6 weeks (p < 0.01), while glutathione peroxida se activity increased (p < 0.05). In term infants, plasma selenium inc reased (p < 0.001), but there was no change in erythrocyte selenium or glutathione peroxidase activity. For preterm infants, glutathione per oxidase activities at weeks 4 and 6 were associated with maximum inspi red oxygen concentration, ventilator pressure, and days of ventialtion . Conclusions: This data is consistent with animal and in vitro eviden ce that glutathione peroxidase may be confounded by oxygen. We conclud e that erythrocyte glutathione peroxidase activity is not a reliable f unctional marker of preterm selenium status in the neonatal period.