Are Plasma Citrulline and Glutamine Biomarkers of Intestinal Absorptive Function in Patients With Short Bowel Syndrome?

• Published in: JPEN. Journal of parenteral and enteral nutrition Vol. 31; no. 1; pp. 1 - 7
• Main Authors: Luo, Menghua, Fernández-Estívariz, Concepción, Manatunga, Amita K., Bazargan, Niloofar, Gu, Li H., Jones, Dean P., Klapproth, Jan-Michael, Sitaraman, Shanthi V., Leader, Lorraine M., Galloway, John R., Ziegler, Thomas R.
• Format: Journal Article
• Language: English
• Published: Silver Spring, MD SAGE Publications 01.01.2007; ASPEN; American Society for Parenteral and Enteral Nutrition
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Biomarkers - blood; Citrulline - pharmacokinetics; Double-Blind Method; Emergency and intensive care: metabolism and nutrition disorders. Enteral and parenteral nutrition; Female; Gastroenterology. Liver. Pancreas. Abdomen; Glutamine - pharmacokinetics; Human Growth Hormone - administration & dosage; Humans; Intensive care medicine; Intestinal Absorption - physiology; Intestine, Small - anatomy & histology; Intestine, Small - metabolism; Male; Medical sciences; Middle Aged; Other diseases. Semiology; Parenteral Nutrition; Prospective Studies; Short Bowel Syndrome - blood; Short Bowel Syndrome - metabolism; Short Bowel Syndrome - therapy; Stomach, duodenum, intestine, rectum, anus; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the digestive system; Human; Nutrition; Intestinal malabsorption; Aminoacid; Digestive diseases; Intestinal disease; Citrulline; Short bowel syndrome; Enteral administration; Parenteral administration; Feeding; Glutamine
• ISSN: 0148-6071; 1941-2444
• DOI: 10.1177/014860710703100101

Sensitive biomarkers for intestinal absorptive function would be clinically useful in short bowel syndrome (SBS). Citrulline (Cit) is a product of the metabolism of glutamine (Gln) and derived amino acids by enterocytes. Cit is produced almost exclusively by the gut, which is also a major site of Gln metabolism. The goals of this study were to examine whether plasma Cit and Gln concentrations are biomarkers of residual small intestinal length and nutrient absorptive functions in adult SBS patients followed prospectively. We studied 24 stable adults with severe SBS receiving chronic parenteral nutrition (PN) in a double-blind, randomized trial of individualized dietary modification± recombinant human growth hormone (GH). During a baseline week, intestinal absorption studies (% absorption of fluid, kcal, nitrogen, fat, carbohydrate, sodium, phosphorus, and magnesium) were performed and concomitant plasma Cit and Gln concentrations determined. Individualized dietary modification and treatment with subcutaneous injection of placebo (n = 9) or GH (0.1 mg/kg daily × 21 days, then 3 times/week; n = 15) were then begun. PN weaning was initiated after week 4 and continued as tolerated for 24 weeks. Repeat plasma amino acid determination and nutrient absorption studies were performed at weeks 4 and 12. Residual small bowel length at baseline was positively correlated with baseline plasma Cit (r = 0.467; p = .028). However, no significant correlations between absolute Cit or Gln concentrations and the percent absorption of nutrient substrates at any time point were observed. Similarly, no correlation between the change in Cit or GLN concentration and the change in % nutrient absorption was observed (baseline vs weeks 4 and 12, respectively). By weeks 12 and 24, 7 and 13 subjects were weaned completely from PN, respectively. However, baseline plasma Cit or Gln did not predict PN weaning at these time points. We concluded that plasma Cit (but not Gln) concentrations appeared to be an indicator of small intestinal length in adult SBS. However, neither plasma Cit nor Gln was a biomarker for intestinal absorptive function in this cohort of patients with SBS. In 24 subjects with severe short bowel syndrome, plasma citrulline concentration was positively correlated with the length of residual small intestine. However, serial measures of plasma citrulline or glutamine concentrations were not significantly correlated with concomitant intestinal macronutrient or micronutrient absorption and did not predict parenteral nutrition dependency during a 24-week follow-up.