Early glucose and sodium trajectories and short-term outcomes in extremely preterm infants

Extremely preterm infants commonly develop marked early changes in plasma glucose and sodium concentrations, but their clinical relevance remains unclear. We therefore aimed to characterize plasma glucose, sodium, and calculated osmolarity, and examine their associations with short-term neonatal outcomes.

We conducted a retrospective single-center cohort study of 42 extremely preterm infants (22₊₀ - 27₊₆ weeks' gestation). Levels, variability, and temporal patterns in serial plasma glucose and sodium measurements, as well as calculated plasma osmolarity, were analyzed during the first postnatal week. Associations with neonatal outcomes were assessed in adjusted analyses.

The lowest glucose value and greater glucose variability during the first postnatal week were associated with duration of mechanical ventilation, bronchopulmonary dysplasia and the composite outcome of bronchopulmonary dysplasia or death. A larger decrease in glucose during the first 4 postnatal days was associated with necrotizing enterocolitis. Plasma sodium and calculated plasma osmolarity during the first postnatal week were associated with surgical ligation of patent ductus arteriosus but showed no consistent associations with the other outcomes studied.

These exploratory findings suggest that associations with subsequent neonatal morbidity were more consistently observed for glucose-derived measures than for plasma sodium or calculated plasma osmolarity. Whether these associations are causal or reflect underlying physiological vulnerability requires further investigation.