627 - Neonatal refeeding syndrome and hyperglycemia during the first week of life in extremely low birth weight infants

Publication Number: 1604.627

Kyoung Joung, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States; Olivia Marchioni, Floating Hospital for Children at Tufts Medical Center, Boston, MA, United States; Michael Prendergast, MassGeneral Hospital for Children, Boston, MA, United States

Background: Extremely low birth weight (ELBW) infants are at risk for neonatal refeeding syndrome (RS) characterized by metabolic derangement and electrolyte imbalances. Hyperglycemia has been described in infants with RS. However, the association of RS with the peak glucose levels during the first week of life in ELBW was not well studied, and whether hyperglycemia in the first week is associated with growth outcomes is not known.

Objective: We aimed to evaluate the association of RS and the peak glucose levels during the first week of life in ELBW infants, and whether hyperglycemia >180 mg/dL during the first week is associated with growth outcomes at NICU discharge.

Design/Methods: We studied 122 ELBW infants born at a level 3 NICU. We defined RS as the occurrence of at least one of the following electrolyte abnormalities within the first week of life: hypophosphatemia ( < 4.0 mg/dL), hypokalemia ( < 3.5mmol/dL), and hypomagnesemia ( < 1.5 mg/dL). We used t-tests and Chi-square tests for the comparison of baseline characteristics in infants with RS and without RS. We used repeated measures generalized linear models to assess the association of RS and the peak glucose levels during the first week of life and the interaction between the time after birth and RS, controlling for gestational age and the birth weight Z-score as covariates. We performed multivariate linear regression analyses to assess the association of hyperglycemia >180mg/dL during the first week and the change of weight, length, and head circumference Z-scores from birth to NICU discharge adjusting for gestational age, the birth size Z-scores for corresponding growth outcomes, and the postmenstrual age (PMA) at discharge.

Results: Mean gestational age was 27.1 ± 2.1 weeks in infants with RS and 26.2 ± 1.9 weeks in infant without RS (p=0.01, Table 1). The means of peak glucose levels were not significantly different between RS and non-RS on each day during the first week, however, there was a significant interaction between time (days after birth) and RS (p value for interaction (time x RS) =0.025). Infants without RS had earlier peak glucose levels and the infants with neonatal RS had later peak glucose levels (Figure 1). There was no significant association between hyperglycemia >180 mg/dL and the growth outcomes at NICU discharge (Table 2).

Conclusion(s): In ELBW infants, there is a difference in the change of peak glucose levels over time between infants with RS and without RS. Infants with neonatal RS had later peak glucose levels compared with infants without RS. Long term effects of RS in glucose and insulin metabolism warrants further investigation.

Table 1. Patient Characteristics
Data presented as N (%) or mean ± SD. P values are from student t-tests continuous variables, and from Chi-square or Fisher's exact tests for categorical variables.

Figure 1. Peak glucose levels during the first week of life in infants with RS and without RS
Repeated measures generalized linear model. P for interaction for time (days of life) x RS = 0.025

Table 2. The association of hyperglycemia and the growth outcomes
Means were adjusted for gestational age, birth size Z-scores for corresponding growth outcomes, and the PMA at NICU discharge.