Longitudinal analysis of urinary I-FABP in extremely preterm infants that develop necrotizing enterocolitis.

Background: Intestinal fatty acid binding protein (I-FABP) is an intestinal epithelial protein detectable in infants with necrotizing enterocolitis (NEC). The longitudinal behavior of I-FABP following NEC or its association with gastrointestinal or neurodevelopmental outcomes is unknown.

Methods: In this secondary analysis of the Preterm Erythropoietin Neuroprotection Trial, we compared infants with and without NEC. Urine I-FABP concentrations in matched infants (n = 70) were measured serially using ELISA and compared using paired analysis. In infants with NEC, the associations of I-FABP levels with short-term outcomes and neurodevelopmental outcomes at 22-26 months corrected age were determined using non-parametric analysis.

Results: Infants with NEC were more likely to have cholestasis, death or severe neurodevelopmental impairment, cerebral palsy, and lower Bayley-III motor scores. Baseline urinary I-FABP levels were similar between groups. When compared to controls, infants with NEC had urinary I-FABP concentrations that were higher at diagnosis (median 11 vs 2.6 ng/ml, p = 0.006) and lower post-NEC (median 1 vs 5 ng/ml, p = 0.002). Diagnosis I-FABP levels were not associated with gastrointestinal or neurodevelopmental outcomes at 22-26 months corrected age.

Conclusions: In extremely preterm infants, urinary I-FABP was elevated at NEC diagnosis and lower post-NEC compared to matched controls. I-FABP levels were not associated with adverse gastrointestinal or neurodevelopmental outcomes.

Impact: Urinary intestinal fatty acid binding protein (I-FABP) levels are increased at diagnosis of NEC and fall to below baseline after NEC in extremely preterm infants. Urine I-FABP levels at NEC diagnosis are not associated with cholestasis, intestinal stricture or obstruction, need for additional intestinal surgery after NEC, or neurodevelopmental outcomes at 22-26 months corrected age. Urine I-FABP levels may be useful in the diagnosis of NEC. Diagnostic I-FABP levels do not predict short-term gastrointestinal or neurodevelopmental outcomes after NEC.