Gut lavage fluid protein concentrations: objective measures of disease activity in inflammatory bowel disease

Fluid obtained by whole gut lavage normally contains traces of immunoglobulin (Ig) G, albumin, and alpha-1-antitrypsin; higher concentrations have been found in patients with inflammatory bowel disease (IBD).

In a prospective study, 53 lavages were performed in 45 IBD patients (27 Crohn's disease, 18 ulcerative colitis), in whom disease activity was simultaneously assessed by Crohn's Disease Activity Index or Powell Tuck index. Concentration of IgG in lavage fluid was measured by enzyme-linked immunosorbent assay, and of albumin and alpha-1-antitrypsin by immunoturbidimetry.

For IgG, concentrations in lavage fluid correlated closely with activity indices: in Crohn's disease, r = 0.723 (P < 0.0001), in ulcerative colitis, r = 0.714 (P < 0.0001). Results for albumin and alpha-1-antitrypsin concentrations were similar to those for IgG, but they were less sensitive in detecting active disease. However, this method cannot be used as a diagnostic test for IBD; normal results were obtained for IgG in 6 (all inactive) of 42 lavages in patients who had unequivocal radiological or endoscopic abnormalities.

Assay of protein concentrations in gut lavage fluid is a simple, objective means of grading disease activity in patients with IBD; its potential uses are likely to be in the evaluation of complex cases and in clinical trials.