Fecal Calprotectin in Small Bowel Crohn's Disease: Is it a reliable tool?

Aims The correlation between fecal calprotectin (FC) levels and small bowel (SB) inflammation in patients with Crohn's Disease (CD) remains a subject of debate. This study aims to investigate the relationship between FC levels and SB inflammatory activity in patients diagnosed with SB CD.

Methods We conducted a retrospective study involving patients with SB CD who underwent small bowel capsule endoscopy (SBCE) and FC testing. Patients with colon inflammation were excluded. Participants were categorized into four groups based on their SB inflammatory status: no inflammation (all three SB tertiles showed Lewis Score (LS)<135); proximal SB inflammation (first and/or second SB tertiles had LS≥135, with no inflammation in the third SB); distal SB inflammation (third SB tertile had LS≥135, with no inflammation in the proximal SB); pan-SB inflammation (both proximal and distal SB showed inflammation).

Results A total of 87 patients were included in the study, with a median age of 35 years, 75.9% were female. The distribution of inflammation among the patients was as follows: no inflammation in 21.8%; proximal inflammation in 4.6%; distal inflammation in 33.3%; pan-SB inflammation in 40.4%.

FC levels exhibited an ascending trend of median values along the SB axis: no inflammation 58 µg/g (33-180); proximal SB inflammation 65 µg/g (30-127.7); distal SB inflammation 122 µg/g (42-507); pan-SB inflammation 400 µg/g (205-852).

Statistically significant differences in FC levels were observed between pan-SB inflammation vs. proximal inflammation (p=0.01), and distal inflammation (p=0.014), with no significant differences in LS.

Additionally, FC showed a positive correlation with LS in the second (r=0.464, p<0.001) and third tertiles (r=0.435, p<0.001), but no correlation was noted in the first tertile.

FC demonstrated good predictive capacity for identifying inflammation in the distal SB and pan-SB vs. no inflammation and proximal inflammation, with an area under the curve of 0.790 and an optimal cutoff value of 229.5 µg/g.

Conclusions FC levels correlate positively with the presence of SB lesions in the second and third tertiles of the small bowel. However, it is not a reliable marker for detecting inflammation in the first tertile, highlighting the importance of conducting a SBCE in these patients. These findings contribute to the understanding of FC as a diagnostic tool in managing SB CD.

Publication History

Article published online:
27 March 2025