Serum citrulline levels correlate with enteral tolerance and bowel length in infants with short bowel syndrome

yObjective To determine if serum levels of CIT (a nonprotein amino acid sythesized by the intestine) correlate with total parenteral nutrition (PN)-independence in children with short bowel syndrome (SBS). Study design We prospectively obtained serum amino acid profiles over a 24-month interval from all infants with SBS 3 weeks to 4 years of age. Remaining small intestine length was recorded at surgery, and percent enteral calories tolerated (enteral calories divided by enteral plus parenteral calories X 100) was determined in 24 infants with SBS and 21 age-matched controls (blood drawn for nongastrointestinal symptoms). Results Mean CIT for controls was 31 +/- 2 mu mol/L. In patients with SBS (n = 24), serum CIT correlated linearly with percent enteral calories (R = 0.85; P < .001) and with bowel length (R = 0.47; P < .03). CIT level in patients with SBS weaned off PN was 30 2 mu mol/L; in those subsequently weaned off PN, 20 2 mu mol/L; and in those who would remain PN-dependent, 11 +/- 2 mu mol/L (P <= .01). Serum CIT 19 mu mol/L had 94% sensitivity and 67% specificity for being off or coming off total PN. Conclusions Serum CIT level > 19 mu mol/L in children with SBS is associated with development of enteral tolerance and may be a useful predictive test.