Use of serum citrulline concentrations from routine newborn screen as a biomarker for necrotizing enterocolitis

Purpose Necrotizing enterocolitis (NEC), a leading cause of mortality and morbidity in preterm neonates, lacks a reliable biomarker. Citrulline is primarily produced by enterocytes and correlates with intestinal function. Serum citrulline concentration (CIT) is routinely measured in routine newborn screening (NBS). The purpose of the study is to test if CIT from NBS may predict the occurrence of NEC and whether it correlates with the time to full feeds (TTFF) and length of stay (LOS), serving as a biomarker of NEC and intestinal health. Methods In a retrospective case control study conducted on neonates with gestational age of 26–32 weeks, we compared CIT levels between cases (neonates with NEC) and controls (next-born neonate). NBS was collected within first 24 h, at day 5 and when the neonates achieved full feeds and were compared using non-parametric tests. Results There was no difference in CIT between the controls and cases on day 1 [11.42 (7.42–14.84 vs. 11.93 (6.85–18.8) µmol/L, p = 0.55], on day 5 [11.99 (7.99–16.55) vs. 13.70 (7.42–26.83) µmol/L, p = 0.05], or at full feeds [14.86 (6.85–25.69) vs. 15.7 (7.42–26.26) µmol/L, p = 0.87]. CIT on day 1 did not correlate with TTFF ( r = 0.08, p = 0.53) or LOS ( r = 0.23, p = 0.06), respectively). Conclusions CIT from routine NBS does not serve as a biomarker to predict NEC in preterm neonates.