From the Guidelines
Calprotectin is a valuable biomarker for differentiating between inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), with a recommended cut-off of 50-100 μg/g for detecting intestinal inflammation. Fecal calprotectin testing is recommended as a non-invasive screening tool when evaluating patients with chronic gastrointestinal symptoms. The test measures levels of calprotectin, a protein released by neutrophils during intestinal inflammation, which appears in stool samples. In IBD, calprotectin levels are typically elevated (>50-100 μg/g, often several hundred or thousand μg/g in active disease), while in IBS, which lacks true inflammation, levels remain normal (<50 μg/g) 1.
Key Points
- Calprotectin has approximately 80-90% sensitivity and specificity for detecting intestinal inflammation, making it useful for initial screening before proceeding to more invasive procedures like colonoscopy 1.
- Calprotectin is also valuable for monitoring disease activity and treatment response in established IBD patients, where rising levels may indicate disease flares before clinical symptoms appear.
- However, it's essential to note that calprotectin can be elevated in other inflammatory conditions like infections, celiac disease, or with NSAID use, so results should be interpreted within the clinical context 1.
- The British Society of Gastroenterology consensus guidelines recommend interpreting calprotectin in the light of the pre-test probability of IBD, and onwards referral to gastroenterology for intermediate range groups is advised 1.
Clinical Application
- Fecal calprotectin testing can be used as a cost-effective measure to prevent unnecessary colonoscopy in patients where IBD is extremely unlikely 1.
- A normal calprotectin level has a high negative predictive value for IBD, while a high level (above 100-250 μg/g) has a higher positive predictive value, but may require further investigation to confirm the diagnosis 1.
- Calprotectin testing can be used to monitor disease activity and response to treatment in IBD patients, and to identify potential disease flares before clinical symptoms appear 1.
From the Research
Role of Calprotectin in Assessing Intestinal Inflammation
- Calprotectin is a biomarker of intestinal inflammation that can be used to distinguish between inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) 2, 3, 4, 5, 6.
- Fecal calprotectin levels are elevated in patients with IBD, and the test has excellent negative predictive value in ruling out IBD in undiagnosed, symptomatic patients 2.
- Calprotectin levels can also be used to predict relapses and detect pouchitis in patients with IBD, and to determine whether clinical symptoms in patients with known IBD are caused by disease flares or noninflammatory complications/underlying IBS 2, 3.
Differential Diagnosis between IBD and IBS
- Calprotectin is useful in the differential diagnosis between IBD and IBS, as it can distinguish between organic and functional disease 4, 6.
- Fecal calprotectin levels are higher in IBD patients than in IBS patients, and can be used to identify patients who require further investigation or treatment 2, 3, 5.
- However, calprotectin levels may also be elevated in some IBS patients, particularly those with coexisting IBS-like symptoms, highlighting the need for careful interpretation of results 3.
Clinical Utility of Calprotectin
- Calprotectin is a noninvasive and reliable marker of intestinal inflammation that can be used in daily clinical practice to assess disease activity and monitor treatment response 4, 5.
- The test is simple, low-cost, and correlates closely with endoscopic activity of IBD, making it a useful tool in the management of IBD patients 2, 5.
- However, the use of calprotectin is not without limitations, and further studies are needed to define its role in certain clinical scenarios, such as collagenous colitis and infectious colitis 4.