Background The fecal calprotectin (FC) level is widely used as a non-invasive method for identifying patients with active Crohn's disease (CD) and ulcerative colitis. Gastrointestinal involvement of Behçet's syndrome (GIBS) shows clinical and endoscopic similarities to CD. A previous study in a small number of Behçet's syndrome (BS) patients with mainly mucocutaneous lesions showed that serum calprotectin levels did not differ between active and inactive patients (1). Another study suggested that FC may help to diagnose GIBS patients (2). We are not aware of studies addressing whether FC levels help to distinguish active GIBS patients from those in remission.

Objectives To determine whether FC levels help predict active disease in GIBS patients.

Methods We collected fecal specimens from 23 GIBS (11 M, 12 F and mean age 44±9 years) patients before colonoscopy. The reasons for colonoscopy were assessing active disease in patients presenting with abdominal pain (with or without diarrhea) (n=9) or confirmation of a remission in asymptomatic patients (n=16). Four symptomatic and 3 asymptomatic patients had active ulcers by endoscopy. On the other hand, 5 symptomatic and 13 asymptomatic patients did not have ulcers by endoscopy. We also included 22 active and 25 inactive CD patients as controls. We used 150 μg/g as the cut-off for a positive FC level. We also looked at the correlation between FC and serum CRP levels, Crohn's disease activity index (CDAI) and disease activity index for intestinal Behçet's disease (DAIBD) scores.

Results FC was >150 μg/g in all of the 7 GIBS patients with ulcers compared to 4/16 of GIBS patients without ulcers (OR, 95%CI: 42 to 888). The mean FC was 1125±800 μg/g (95%CI: 341 to 1908) among symptomatic patients with ulcers (n=4) and 209±213 μg/g (95%CI: 22 to 396) among symptomatic patients without ulcers (n=5). On the other hand, the mean FC was 243±73 μg/g (95%CI: 158 to 328) among asymptomatic patients with ulcers (n=3) and 95±160 μg/g (95%CI: 0.4 to 189) among asymptomatic patients without ulcers (n=11). Among CD patients, 16/25 active patients and 3/22 patients in remission had FC level >150 μg/g (OR, 95%CI: 11 to 49). There was a low correlation between FC and serum CRP levels (r=0.3, p=0.1), a moderate correlation between FC levels and CDAI scores (r=0.5, p=0.02) and very low correlation between FC and DAIBD scores (r=0.01, p=0.9). Among the 4 GIBS patients who had high FC levels despite being in remission for gastrointestinal involvement, 1 had active mucocutaneous lesions, 1 had concomitant macrophage activation syndrome, and 1 had polycythemia vera with trisomy 8. None of the patients were receiving NSAIDs that could increase FC levels.

Conclusions Pending the study of more number of patients, FC may turn out to be a useful non-invasive tool for ruling out active gastrointestinal lesions in asymptomatic GIBS patients. A high FC level demands caution for the presence of active ulcers especially in symptomatic patients, but whether the presence of other BS manifestations can cause false positive results remains to be studied.

1. Oktayoglu P et al. Scand J Clin Lab Invest. 2015

2. Kim DH et al. ECCO.2014

Disclosure of Interest None declared