Background and Aims: Non-invasive biomarkers are gaining interest for monitoring disease activity in patients with inflammatory bowel diseases (IBD). Fecal calprotectin is a reliable biomarker but patients often report the collection of feces being unpleasant and cumbersome. In this study, we aimed to assess if salivary calprotectin could be used as a non-invasive biomarker to determine disease activity instead of fecal calprotectin.

Methods: In this cross-sectional explorative cohort study, stimulated saliva was collected from patients with an established IBD diagnosis and healthy controls. The concentration of calprotectin in saliva was determined by a particle-enhanced turbidimetric immunoassay. Intestinal disease activity was assessed with fecal calprotectin levels and the Harvey-Bradshaw Index (HBI) or Simple Clinical Colitis Activity Index (SCCAI). Missing data were handled using multiple imputation.

Results: Sixty-three patients (41 Crohn’s disease and 22 ulcerative colitis) and 11 controls were included. Patients had a mean fecal calprotectin of 138.78 µg/g and a median salivary calprotectin of 1.87 mg/L. No significant correlation was found between salivary calprotectin and fecal calprotectin levels (p=0.495). When patients were stratified in two subgroups based on a fecal calprotectin cut-off value of 250 µg/g, there were no significant differences in salivary calprotectin levels between both patient groups (p=0.641) and between patients and healthy controls (p=0.248). Also, salivary, and fecal calprotectin levels were not significantly different when stratifying patients in two subgroups, active disease and remission, using HBI/SCCAI scores. Conclusions: Salivary calprotectin does not correlate to fecal calprotectin and disease activity scores in patients, making it unreliable for assessing IBD activity.


inflammatory bowel disease, calprotectin, saliva, biomarker, ulcerative colitis, Crohn’s disease, disease activity