title: The relationship between fasting plasma citrulline concentration and small intestinal function in the critically ill.
abstract: BACKGROUND
  In this study, we aimed to evaluate whether fasting plasma citrulline concentration predicts subsequent glucose absorption in critically ill patients.
  
  
  METHODS
  In a prospective observational study involving 15 healthy and 20 critically ill subjects, fasting plasma citrulline concentrations were assayed in blood samples immediately prior to the administration of a liquid test meal (1 kcal/ml; containing 3 g of 3-O-methylglucose (3-OMG)) that was infused directly into the small intestine. Serum 3-OMG concentrations were measured over the following 4 hours, with the area under the 3-OMG concentration curve (AUC) calculated as an index of glucose absorption.
  
  
  RESULTS
  The groups were well matched in terms of age, sex and body mass index (BMI) (healthy subjects versus patients, mean (range) values: age, 47 (18 to 88) versus 49 (21 to 77) years; sex ratio, 60% versus 80% male; BMI, 25.2 (18.8 to 30.0) versus 25.5 (19.4 to 32.2) kg/m(2)). Compared to the healthy subjects, patients who were critically ill had reduced fasting citrulline concentration (26.5 (13.9 to 43.0) versus 15.2 (5.7 to 28.6) μmol/L; P < 0.01) and glucose absorption (3-OMG AUC, 79.7 (28.6 to 117.8) versus 61.0 (4.5 to 97.1) mmol/L/240 min; P = 0.05). There was no relationship between fasting citrulline concentration and subsequent glucose absorption (r = 0.28; P = 0.12).
  
  
  CONCLUSIONS
  Whereas both plasma citrulline concentrations and glucose absorption were reduced in critical illness, fasting plasma citrulline concentrations were not predictive of subsequent glucose absorption. These data suggest that fasting citrulline concentration does not appear to be a marker of small intestinal absorptive function in patients who are critically ill.
authors.affiliation: Intensive Care Unit, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia.
authors.forename: Alexis
authors.initials: A
authors.lastname: Poole
authors.affiliation: Intensive Care Unit, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia.|Discipline of Acute Care Medicine, University of Adelaide, Frome Road, Adelaide, South Australia, 5000, Australia.
authors.forename: Adam
authors.initials: A
authors.lastname: Deane
authors.affiliation: Intensive Care Unit, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia.|Discipline of Acute Care Medicine, University of Adelaide, Frome Road, Adelaide, South Australia, 5000, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Summers
authors.affiliation: Genetics and Molecular Pathology, SA Pathology, Frome Road, Adelaide, South Australia, 5000, Australia.
authors.forename: Janice
authors.initials: J
authors.lastname: Fletcher
authors.affiliation: Intensive Care Unit, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia. marianne.chapman@health.sa.gov.au.|Discipline of Acute Care Medicine, University of Adelaide, Frome Road, Adelaide, South Australia, 5000, Australia. marianne.chapman@health.sa.gov.au.
authors.forename: Marianne
authors.initials: M
authors.lastname: Chapman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002956:Citrulline / Q000097:blood*; D016638:Critical Illness; D004750:Enteral Nutrition; D005215:Fasting / Q000097:blood*; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption; D007421:Intestine, Small / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D002956:Citrulline; D005947:Glucose