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Plasma bilirubin level and oxidative stress in preterm infants
C Dani1, E Martelli, G Bertini
1Division of Neonatology, Careggi University Hospital of Florence, Florence, Italy. dani@cesit1.unifi.it
Insights
Changes in plasma bilirubin levels in preterm infants correlate with antioxidant capacity and oxidative stress. A decrease in bilirubin coincided with improved antioxidant function and reduced oxidative stress.
Area of Science:
- Neonatal Medicine
- Biochemistry
- Pediatric Research
Background:
- Hyperbilirubinemia is common in preterm infants.
- The role of bilirubin in the neonatal antioxidant system is not fully understood.
- Oxidative stress is a significant concern in preterm neonates.
Purpose of the Study:
- To investigate the relationship between plasma total bilirubin levels (Btot) and markers of oxidative stress and antioxidant capacity in preterm infants.
- To test the hypothesis that bilirubin levels influence the antioxidant system.
Main Methods:
- Studied 22 healthy preterm infants with non-haemolytic hyperbilirubinemia.
- Measured plasma total bilirubin (Btot), total hydroperoxide (TH), protein SH groups, and total antioxidant capacity (TAC) at baseline and 24 hours.
- Analyzed correlations between these parameters.
Main Results:
- No direct correlation was found between Btot and TH, TAC, or protein SH groups.
- Significant correlations were observed between TH and TAC, TH and protein SH groups, and TAC and protein SH groups.
- A decrease in plasma bilirubin was concurrent with an increase in TAC and a decrease in TH.
Conclusions:
- Plasma bilirubin levels appear to influence the antioxidant system and oxidative stress in preterm infants.
- The observed changes suggest bilirubin's antioxidant properties may be less significant than the pro-oxidant effects of heme oxygenase activity.
- Further research is needed to elucidate the complex interplay between bilirubin metabolism and oxidative balance in neonates.
Objective:
To assess the hypothesis that changes in plasma total bilirubin levels (Btot) can influence the antioxidant system and oxidative stress in preterm infants.
Methods:
Twenty two healthy preterm infants who presented with visible non-haemolytic hyperbilirubinaemia were studied at the mean (SD) age of 3.7 (1.5) days. Btot, plasma total hydroperoxide concentration (TH), plasma protein SH group concentration, and total antioxidant capacity of the plasma (TAC) were measured at study entry and after 24 hours.
Results:
Btot did not correlate with TH, TAC, or protein SH group concentration, but a significant correlation was found between TH and TAC, TH and protein SH groups, and TAC and protein SH groups, both at study entry and after 24 hours.
Conclusion:
The decrease in plasma bilirubin was contemporary with an increase in plasma antioxidant capacity and decrease in oxidative stress in preterm infants. This may be the result of the pro-oxidant effect of haem oxygenase, mediated by iron release, which may outcompete the antioxidant properties of bilirubin.