Plasma citrulline after small bowel transplantation: Effect of time from transplantation, acute cellular rejection, and renal failure

Background: Plasma citrulline concentration (CIT) depends on its synthesis by enterocytes and its catabolism by renal tubules. To evaluate CIT applicability as a marker of acute cellular rejection (ACR) after intestinal transplantation (ITx), CIT was investigated according to time from ITx, episodes of ACR, and creatinine clearance (CrCl). Methods: Twenty-four adult ITx recipients were prospectively studied. The results were compared with those of 19 healthy controls (HCs) and of 29 patients with chronic renal failure (CRF). Results: In ITx recipients, CIT was lower than in HCs during the first two postoperative weeks; it then progressively increased and reached the range observed in HCs, approximately between the 31st and the 45th postoperative day. A positive association with postoperative days (R = 0.63; p < 0.0001) and a negative association with CrCl (R = -0.57; p < 0.0001) were observed. CIT was higher in patients with CRF than in HCs (p < 0.0001). CIT sensitivity and specificity in detecting ACR after the 45th postoperative day were 38% and 83%, using CIT threshold observed in HCs, and 69% and 77%, respectively, using CIT threshold adjusted for CRF degree. Conclusions: Adjusting CIT threshold for CRF degree almost doubled the sensitivity of CIT as a non-invasive marker of ACR in ITx recipients. © 2015 John Wiley