Risk Factors and Effects of Severe Late-Onset Hyponatremia on Long-Term Growth of Prematurely Born Infants.

PURPOSE

Sodium is an essential nutritional electrolyte that affects growth. A low serum sodium concentration in healthy premature infants beyond 2 weeks of life is called late-onset hyponatremia (LOH). Here, we investigated the association between LOH severity and growth outcomes in premature infants.

METHODS

Medical records of premature infants born at ≤32 weeks of gestation were reviewed. LOH was defined as a serum sodium level <135 mEq/L regardless of sodium replacement after 14 days of life. Cases were divided into two groups, <130 mEq/L (severe) and ≥130 mEq/L (mild). Characteristics and growth parameters were compared between the two groups.

RESULTS

A total of 102 premature infants with LOH were included. Gestational age ([GA] 27.7 vs. 29.5 weeks, <0.001) and birth weight (1.04 vs. 1.34 kg, <0.001) were significantly lower in the severe group. GA was a risk factor of severe LOH (odds ratio [OR], 1.328, =0.022), and severe LOH affected the development of bronchopulmonary dysplasia (OR, 2.950, =0.039) and led to a poor developmental outcome (OR, 9.339, =0.049). Growth parameters at birth were lower in the severe group, and a lower GA and sepsis negatively affected changes in growth for 3 years after adjustment for time. However, severe LOH was not related to growth changes in premature infants.

CONCLUSION

Severe LOH influenced the development of bronchopulmonary dysplasia and developmental outcomes. However, LOH severity did not affect the growth of premature infants beyond the neonatal period.