Is an increased intestinal permeability a valid predictor of relapse in Crohn disease?

Background: An increased intestinal permeability (IP) may be a pathogenetic factor in Crohn disease (CD). Increases in IP could be an indicator of subclinical disease and precede clinical relapses. We examined whether an increased IP is a valid predictor of relapse in CD. Methods: 27 patients with CD in remission (CDAI < 150) and 22 healthy controls ingested 3.7 MBq of Cr-51-EDTA, 20 kBq of C-14-mannitol and 5 g of unlabelled mannitol in 100 ml of distilled water. The percent urine excretion (24 h) of labelled markers was determined. Patients were followed for I year or until relapse, defined as CDAI > 150 and > 50 from baseline. Results: Median (25th-75th percentiles). The excretion of Cr-51-EDTA was 1.55% (1.13%-2.53%) for patients and 1.20% (1.11%-1.44%) for controls (P = 0.04). Three of 9 patients with a raised, and 6 of 18 patients with a normal, Cr-51-EDTA excretion relapsed (P = 1.00: Fisher's exact test). Thus, the specificity and sensitivity of the 51Cr-EDTA test as a predictor of relapse was 67% and 33%, respectively. The Cr-51-EDTA/C-14-mannitol index was 0.060 (0.037-0.093) for patients and 0.045 (0.038-0.054) for controls (P = 0.06). Four of 12 patients with a raised, and 5 of 15 patients with a normal. index relapsed (P = 1.00; Fisher's exact test). Thus. the specificity and sensitivity of the index test as a predictor of relapse was 56% and 44%. respectively. For controls and patients in remission. who were tested twice, variability of and fluctuations in both the 51Cr-EDTA excretion and the index were greatest for patients. Conclusions: This study supports previous findings of an increased IP in patients with CD. Although fluctuations in the permeation of markers were pronounced in CD, neither the excretion of Cr-51-EDTA nor the Cr-51-EDTA/C-14-mannitol index test were valid predictors of relapse in CD.