[Fecal calprotectin in differential diagnosis of irritable bowel syndrome]

To assess the value of fecal calprotectin as a non-invasive screening biomarker in differential diagnosis of irritable bowel syndrome compared with fecal occult blood test (FOBT), erythrocyte sedimentation (ESR) or C reactive protein (CRP).

Subjects were a total of 240 persons, including 60 patients with irritable bowel syndrome, 60 patients with colorectal cancer, 60 patients with chronic inflammation, and 60 healthy controls. 5 g fecal samples were collected within one week of endoscopy or before surgical operation. Fecal calprotectin was measured by an enzyme-linked immunosorbent assay (ELISA) kit in spot stool samples. At the same time, FOBT was measured; the results of ESR and CRP in hospital lab were collected.

The median of fecal calprotectin concentrations were 12.21 mg/kg and 15.36 mg/kg in IBS and healthy controls, respectively. There was no statistical significance of calprotectin concentration between patients with IBS and healthy controls (P>0.05). The median of fecal calprotectin concentrations were 159.00 mg/kg and 466.00 mg/kg in colorectal cancer and chronic inflammation respectively. There were statistical significance between patients with chronic inflammation, colorectal cancer, and others (P<0.01). The maximal calprotctin concentration was with chronic inflammation; the medium with colorectal cancer; the minimum with IBS and healthy controls. When the cut-off limit was set as 50 mg/kg of fecal calprotectin, the positive rates of colorectal cancer, chronic inflammation, IBS and healthy controls were 85.0%, 91.7%, 10%, and 5%,respectively. Fecal calprotectin was much superior to FOBT, ESR and CRP.

Fecal calprotectin as a non-invasive screening biomarker in the differential diagnosis of IBS and symptomatic chronic large intestinal organic disease was better than FOBT, ESR and CRP. It was simple, inexpensive, repeatable and no-invasive. It can be used as a biomarker in exclusion from related organic diseases before the diagnosis of irritable bowel syndrome.