Plasma Citrulline Concentrations in Neonates With or Without Gastrointestinal Disease During Periods of Parenteral and Enteral Nutrition

Abstract

Citrulline is synthesized primarily in enterocytes. Retrospective work revealed higher plasma concentrations in patients without gastrointestinal (GI) disease than in those with GI disease, regardless of bowel resection, leading us to speculate whether it could be used as a marker of gut function prospectively. Our purpose was to analyze plasma citrulline in these patients, comparing a period of exclusive parenteral nutrition (PN) vs both PN and enteral nutrition (PN/EN). Premature neonates were included in this study. Plasma samples were collected during 2 periods, PN and PN/EN. They were classified into groups: patients without GI disease (Group 1), patients with GI disease without resection (Group 2), and patients with GI disease and resection (Group 3). Plasma was analyzed by high-performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). Data were described as median with ranges. Fifty patients were recruited for this study, from which 164 samples were obtained and analyzed by LC-MS. Median plasma citrulline concentrations were 12.3 (5.6-39.4) µmol/L, 14.9 (6.8-39.8) µmol/L, and 10.8 (2.0-23.6) µmol/L for Groups 1, 2, and 3, respectively. After Bonferroni correction, only Group 3 had a significantly different median from the others. No differences were observed within periods of nutrition (PN vs PN/EN). Postconceptual age (PCA), among others, was assessed to determine differences for which the former demonstrated significance. Premature neonates with bowel resection had lower plasma citrulline concentrations, confirming its role as gut mass marker, though without differences during transitional feeding. PCA may affect expression of this protein.