Exclusive breast-feeding and postnatal changes in blood sodium, ketone, and glucose levels

Blood sodium and ketone are parameters of dehydration and fasting, respectively. Little is known, however, about the postnatal changes in these parameters in healthy, term, exclusively breast-fed neonates.

Capillary blood sodium, β-hydroxybutyrate (β-OHB), and glucose levels in 628 samples obtained from 392 healthy, term, exclusively breast-fed neonates during the first 12-143 h of life were examined.

Blood sodium and β-OHB gradually increased and reached a peak at 48-59 h of life (mean blood sodium, 142.3 ± 2.8 mEq/L; mean blood sodium increase, 3.3 mEq/L; mean β-OHB, 1.16 ± 0.46 mmol/L; mean β-OHB increase, 0.65 mmol/L), and then gradually decreased and reached a nadir at 120-143 h of life. Blood glucose gradually decreased and reached a nadir at 48-59 h of life (mean, 62.4 ± 12.2 mg/dL; mean decrease, 4.7 mg/dL), and then gradually increased and peaked at 120-143 h of life. These changes were synchronized with changes in weight-loss percentage.

The postnatal changes in blood sodium, ketone, and glucose levels during the first 12-143 h of life are described in healthy, term, exclusively breast-fed neonates. The parameters seemed to be associated with the sufficiency of the breast-milk supply. These results can serve as normal reference values for healthy, term, exclusively breast-fed neonates during the early postnatal period.