Citrulline and the gut.
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.
Curis
Emmanuel
E
Laboratoire de Biomathématiques, Faculté de Pharmacie, Université Paris Descartes, Paris, France. emmanuel.curis@univ-paris5.fr
Crenn
Pascal
P
Cynober
Luc
L
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
D015415:Biomarkers; D002956:Citrulline