BACKGROUND: Fasting plasma citrulline (p-citrulline) is a marker of functional enterocyte mass. However, the optimal timing of measurement in relation to meals has yet to be clarified. Furthermore, p-citrulline has been proposed to be a surrogate marker for small bowel length and intestinal absorption parameters in short bowel syndrome patients with intestinal failure (SBS-IF).

MATERIALS AND METHODS: Eight patients with SBS-IF and 8 healthy controls (HCs) were given a standardized mixed test meal, and p-citrulline was measured 15 minutes before and 60, 120, and 180 minutes after completion of the meal. The patients with SBS-IF had their intestinal absorption of wet weight, energy, macronutrients, and electrolytes measured in relation to 72-hour metabolic balance studies. We investigated the possible correlations between p-citrulline and short bowel length, absorptive parameters, and the dependence on parenteral support (PS).

RESULTS: In the patients with SBS-IF, we found a 12% ( P = .041) reduction in postprandial citrulline levels after 180 minutes. In the HCs, there was a 13% postprandial reduction at 60 minutes ( P = .018). No significant correlations between fasting p-citrulline and bowel length, bowel absorptive function, or the dependence on PS were found. Even when excluding 2 patients in whom the intestinal absorption was adjacent to the intestinal insufficiency borderlines, these correlations were not significant.

CONCLUSION: Based on findings in this small study, the optimal timing of p-citrulline measurement is on fasting samples. However, p-citrulline seems insufficiently discriminative to serve as a valid biomarker of bowel length, bowel absorptive function, or dependence on PS in patients with SBS-IF.