134 - Neonatal refeeding syndrome (RS) is associated with postnatal growth failure in extremely low birth weight infants

Poster Number: 134
Publication Number: 134.507

Background: Extremely low birth weight (ELBW) infants are at risk for neonatal refeeding syndrome (RS) characterized by electrolyte imbalances such as hypophosphatemia and hypokalemia. Previous studies showed that intrauterine growth restriction is associated with higher incidence of neonatal RS, however, whether postnatal growth failure is associated with RS remains uncertain.

Objective: We aimed to evaluate the association of neonatal hypophosphatemia ( < 4.5mg/dL) and hypokalemia ( < 3.5mg/dL) within the first week of life and 1) antenatal and perinatal factors such as maternal preeclampsia, gestational diabetes, chorioamnionitis, and small for gestational age (SGA) status, 2) postnatal growth failure ( < 10th %ile weight-for-gestational age) at discharge and changes in weight, length, and head circumference (Hc) Z-scores from birth to NICU discharge.

Design/Methods: We studied 111 infants born at a level 3 NICU with birth weight < 1,000 g. We used t-tests and chi square tests to analyze the association between hypophosphatemia/hypokalemia and antenatal and perinatal factors and growth failure < 10th %ile at discharge. We used generalized estimating equations to analyze the association between hypophosphatemia/hypokalemia and changes of weight, length, and Hc Z-scores from birth to NICU discharge adjusting for gestational age, birth weight Z-score, and multiple birth.

Results: Mean gestational age was 26.6±2.0 weeks, and the mean birth weight was 764±146g. There was a significant association between hypophosphatemia and maternal preeclampsia (p < 0.001), and SGA status (p < 0.001), and weight < 10th %ile at discharge (p < 0.001, Table 1). Birth length and Hc Z-scores were lower in infants with hypophosphatemia vs. those without hypophosphatemia (Table 1). There was no significant association between hypokalemia and these characteristics (p=0.05 for preeclampsia, p=0.09 for SGA, p=0.44 for weight < 10th %ile at discharge). There was no association between hypophosphatemia/hypokalemia and maternal chorioamnionitis and gestational diabetes. In multivariate analysis adjusted for gestational age, birth weight Z-score, and multiple birth, hypophosphatemia was associated with higher incidence of weight < 10th %ile at discharge (B=0.16 (95% CI 0.03-0.29), p=0.02, Table 2), but hypokalemia was not associated with it. Changes of weight, length, Hc Z-scores from birth to discharge were not significantly associated with hypophosphatemia or hypokalemia (Table 3).

Conclusion(s): Neonatal RS is associated with postnatal growth failure. Long-term follow up is warranted to monitor postnatal growth and weight gain in ELBW infants.