Background Preterm neonates are subjected to excessive formation of reactive oxygen species, while having reduced antioxidant defense systems. The resulting redox imbalance is strongly associated with diseases like bronchopulmonary dysplasia. In preterm infants on postnatal day 2, concentrations of glutathione (GSH), the most important intracellular antioxidant, increased upon amino acid (AA) administration, whereas fractional synthesis rate (FSR) did not. We hypothesized that GSH synthesis increases earlier postnatally.

Objective To compare GSH synthesis rates in erythrocytes on postnatal day 1 and 2 of preterm infants receiving AA from birth onwards.

Methods We conducted a stable isotope study in preterm infants receiving AA (2.4 g/kg/d) directly following birth. A primed continuous infusion of [1-13C]glycine was administered either on postnatal day 1 or 2 (6.5±4 and 35±3 hours postnatally, respectively) to determine FSR and concentration of GSH. Absolute synthesis rates (ASR) were calculated from the product of FSR and GSH concentration.

Results Birth weight, gestational age and AA intake were not different while energy intake was higher on day 2. Erythrocyte GSH concentration increased significantly with time, while the FSR was not significantly different (see table).

Conclusion GSH concentration in preterm infants is increased on day 2 compared to directly after birth, without an accompanying rise in GSH synthesis rate, suggesting that GSH consumption is decreased upon AA administration. Whether AA serve as antioxidants themselves remains to be elucidated.