Hot topics in postsmall bowel transplantation: noninvasive graft monitoring including stool calprotectin and plasma citrulline

Abstract

Long-term success in intestinal transplantation could be significantly improved by the development of a reliable noninvasive marker of rejection, allowing early diagnosis and treatment without the need for repeated biopsy procedures. At present, no single test appears sufficiently reliable to replace the need for invasive testing. Falling plasma citrulline levels may correlate with mucosal damage already done, but do not appear to be specific for rejection or provide clinically useful prediction of an event in advance of its occurrence. Similarly, rising stool calprotectin levels are correlated with pathologic diagnosis of rejection, but do not appear to have sufficient predictive value. Both tests appear to be best described as exclusionary, in that if their values are 'normal', rejection is less likely, but each is hampered by wide variability within and between patients. These approaches and others are reviewed in an outline of the current progress towards developing a clinically useful noninvasive tool for graft monitoring.