Abdominal pain, rectal bleeding, or altered defecation pattern are patient complaints frequently encountered by general practitioners (GPs). Most of these complaints have a nonorganic background, and the prevalence of organic bowel disease (OBD)—including inflammatory bowel disease (IBD) and colorectal cancer (CRC)—in primary care patients is approximately 7%. Distinguishing OBD from non-OBD needs to be timely, and the diagnostic workup aims at not missing OBD patients, who require subsequent work-up and referral to secondary care.
Fecal calprotectin, a degradation product from neutrophil granulocytes from the mucosal layer of the colon, is increased when colonic inflammation is present and has been shown to have high diagnostic accuracy for discriminating OBD from non-OBD in secondary care. It is stable in feces for as long as 1 week at room temperature. On the other hand, immunochemical fecal occult blood tests (iFOBTs) detect hemoglobin and its early degradation products, which may indicate the presence of polyps or adenocarcinoma of the colon