title: Citrulline and the gut.
abstract: OBJECTIVE
  Citrulline, a nonprotein amino acid, is an important source of endogenous arginine. The gut is the main source of citrulline in humans. Hence, citrulline is a potential biomarker of short bowel function. Conversely, citrulline uptake by the gut is important for an oral supply of this amino acid as an alternative to arginine. This review discusses these two aspects of citrulline, as well as the recent developments in the understanding of its metabolism.
  
  
  RESULTS
  Citrullinemia is such an efficient marker when the active mass of the bowel is affected that it can be used as a prognostic marker for parenteral nutrition weaning (if citrullinemia is >20 micromol/l) and as a factor for deciding between parenteral and enteral nutrition (as long as the pathology is considered). Citrullinemia should be used with care as a marker either of the intestinal absorption or following small bowel transplantation.
  
  
  CONCLUSIONS
  Citrulline is easily taken up by the gut, with a broad set of transporters that can remove it from the lumen in the enterocytes. This is confirmed by pharmacokinetic studies and the efficacy is so great that oral complementation with citrulline seems more efficient than complementation with arginine to provide arginine.
authors: Laboratoire de Biomathématiques, Faculté de Pharmacie, Université Paris Descartes, Paris, France. emmanuel.curis@univ-paris5.fr
authors: Emmanuel
authors: E
authors: Curis
authors: Pascal
authors: P
authors: Crenn
authors: Luc
authors: L
authors: Cynober
mesh_terms: D015415:Biomarkers / Q000097:blood; D002956:Citrulline / Q000097:blood*; D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000473:pathology*; D009751:Nutritional Requirements; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012778:Short Bowel Syndrome / Q000378:metabolism / Q000473:pathology
chemical_list: D015415:Biomarkers; D002956:Citrulline