Fecal calprotectin (FC), a protein released by neutrophils, is a reliable and non-invasive biomarker of intestinal inflammation. Its primary value lies in its ability to differentiate functional bowel disorders from organic diseases, thereby guiding the indication for endoscopic evaluation. This study aims to assess the diagnostic value of FC and its role in determining the need for colonoscopy.

A retrospective study was conducted, including patients who underwent fecal calprotectin measurement prior to a total colonoscopy over a five-year period, from January 2019 to July 2025.

Among 1,336 patients who underwent colonoscopy, 71 were included in this study. A slight female predominance was observed (56%; sex ratio F/M = 1.2), with a median age of 42 years.

Regarding medical history, diabetes mellitus and previous appendectomy were each present in 9.5% of cases (n=7), while a family history of inflammatory bowel disease (IBD) and chronic smoking were reported in 4% (n=3).

Clinically, the main presenting symptoms were Koenig’s syndrome in 56% (n=40), mucoid diarrhea in 45% (n=32), alternating diarrhea/constipation in 17% (n=12), and rectal bleeding in some cases.

Biochemically, FC levels were >1000 µg/g in 16.9% (n=12), between 250–1000 µg/g in 53.5% (n=38), and <50 µg/g in a single patient.

Endoscopically, 59% (n=42) of colonoscopies were consistent with IBD findings: Crohn’s disease was diagnosed in 45% of patients (n=32), most commonly involving the ileum or ileocolic region, with perianal involvement observed in 9.8% (n=7). Ulcerative colitis was identified in 14% (n=10), predominantly with left-sided or pancolonic distribution. In 7% of patients (n=5), nonspecific inflammatory lesions were identified, including erosive ileitis, terminal ulcerative ileitis, nodular ileitis, and erosive rectosigmoiditis, without histopathological confirmation. Two additional cases demonstrated ulceroinfiltrative masses suggestive of neoplastic processes. Conversely, 29% (n=21) of colonoscopies were completely normal.

This study highlights a significant correlation between fecal calprotectin levels and colonoscopy findings, with 71% of examinations revealing endoscopic abnormalities. These results confirm the diagnostic relevance of FC testing, particularly for IBD screening, while also suggesting a high sensitivity in detecting colorectal carcinoma. However, although elevated FC levels are often associated with severe endoscopic lesions, they do not provide absolute predictive value.