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

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.

27 patients with CD in remission (CDAI <150) and 22 healthy controls ingested 3.7 MBq of 51Cr-EDTA, 20 kBq of 14C-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 1 year or until relapse, defined as CDAI > 150 and > 50 from baseline.

Median (25th-75th percentiles). The excretion of 51Cr-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, 51Cr-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 51Cr-EDTA/14C-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.

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 51Cr-EDTA nor the 51Cr-EDTA/14C-mannitol index test were valid predictors of relapse in CD.