Crenn et al correlated plasma citrulline concentration with absorptive capacity in patients with the short bowel syndrome. The higher the plasma citrulline concentration the better the intestinal absorptive capacity. The authors are from Hopital Lariboisiere-Saint Lazare and Hopital St. Antoine in Paris.


Citrulline is the amino acid N-(aminocarbonyl)-L-ornthine which was first isolated from the watermelon (Citrullus vulgaris). The molecular weight is 175.19 Daltons and 1 mg/dL = 0.5708 µmol/L.


Patients were evaluated at least 2 years after the last "digestive circuit modification" which allows for intestinal adaptation.


Patients were given oral feedings without enteral support. Parenteral nutrition was stopped at least 8 hours before blood collection and after an overnight fast.


estimated small bowel length in cm =

= 4.348 * ((plasma citrulline concentration in µmol/L) - 5.68) =

= (4.348 * (plasma citrulline concentration)) - 24.7


For a patient who is hyperphagic (intake 2.4 +/- 0.6 times resting energy expenditure and 2.2 g protein +/- 0.6 per kg):


estimated small bowel length in cm in a hyperphagic patient =

= 6.25 * ((plasma citrulline concentration in µmol/L) - 4.47) =

= (6.25 * (plasma citrulline)) - 27.9


For a patient who is normophagic (intake approximately half that of the hyperphagic patient):


estimated small bowel length in cm in a normophagic patient =

= 6.67 * ((plasma citrulline concentration in µmol/L) - 11.7) =

= (6.67 * (plasma citrulline)) - 78


A plasma citrulline concentration > 20 µmol/L identifies patients with no or transient intestinal failure, while a plasma citrulline concentration <= 20 µmol/L is associated with permanent intestinal failure (sensitivity 92% and specificity 90%).


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