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

Objective

To determine if serum levels of CIT (a nonprotein amino acid synthesized 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 × 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 μmol/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 μmol/L; in those subsequently weaned off PN, 20 ± 2 μmol/L; and in those who would remain PN-dependent, 11 ± 2 μmol/L (P ≤.01). Serum CIT ≥19 μmol/L had 94% sensitivity and 67% specificity for being off or coming off total PN.

Conclusions

Serum CIT level >19 μmol/L in children with SBS is associated with development of enteral tolerance and may be a useful predictive test.

ALA, alanine, ARG, arginine, CIT, citrulline, GLN, glutamine, GLU, glutamate, GLY, glycine, HIS, histidine, ILE, isoleucine, LEU, leucine, LYS, lysine, MET, methionine, NEC, necrotizing enterocolitis, ORN, ornithine, PHE, phenylalanine, PN, parenteral nutrition, PRO, proline, SBS, short bowel syndrome, SEM, standard error of the mean, SER, serine, TAU, taurine, THR, threonine, TPN, total parenteral nutrition, TRP, tryptophan, TYR, tyrosine, VAL, valine