From the Guidelines
Elevated fecal calprotectin levels indicate active inflammation in the gastrointestinal tract, particularly in the intestines, and are commonly associated with inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis. The significance of elevated calprotectin lies in its ability to help differentiate between inflammatory and non-inflammatory gastrointestinal disorders, potentially reducing the need for invasive procedures like colonoscopy in initial evaluations. The degree of elevation often correlates with the severity of inflammation, making it useful for monitoring disease activity and treatment response in patients with known IBD, as suggested by the AGA clinical practice guideline on the role of biomarkers for the management of ulcerative colitis 1. However, calprotectin is not disease-specific, so results should always be interpreted in the context of clinical symptoms and other diagnostic findings. Elevated levels (typically above 50-100 μg/g, though cutoff values may vary between laboratories) can also be associated with other conditions such as intestinal infections, colorectal cancer, or with use of certain medications like NSAIDs, as noted in the british society of gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults 1. In patients with UC in symptomatic remission, the AGA suggests using fecal calprotectin <150 mg/g to rule out active inflammation and avoid routine endoscopic assessment of disease activity 1. The use of fecal calprotectin as a biomarker for monitoring and diagnosis of IBD is supported by various studies, including those published in Gastroenterology 1, highlighting its value in clinical practice for managing patients with IBD. It's also important to consider the downstream consequences of testing and associated costs, as well as the potential for elevated biomarkers in otherwise asymptomatic individuals to lead to high patient anxiety, as discussed in the AGA clinical practice guideline on the role of biomarkers for the management of ulcerative colitis 1. Overall, the interpretation of elevated fecal calprotectin levels should be done with caution, considering both the clinical context and the potential limitations of the test, to ensure appropriate management and minimize unnecessary procedures or treatments.
From the Research
Significance of Elevated Calprotectin Levels
Elevated calprotectin levels, particularly fecal calprotectin, are significant in the diagnosis and management of inflammatory bowel disease (IBD) 2, 3. The protein is a marker of intestinal inflammation and has been shown to correlate well with histological inflammation detected by colonoscopy with biopsies.
Applications in Inflammatory Bowel Disease
- Fecal calprotectin levels are markedly elevated in IBD, making it a useful noninvasive marker for neutrophilic intestinal inflammation 2.
- It can predict relapses and detect pouchitis in patients with IBD 2.
- Fecal calprotectin can differentiate IBD from irritable bowel syndrome (IBS) due to its excellent negative predictive value in ruling out IBD in undiagnosed, symptomatic patients 2, 3.
- It may be useful in determining whether clinical symptoms in patients with known IBD are caused by disease flares or noninflammatory complications/underlying IBS 2.
Clinical Utility Beyond IBD
- Fecal calprotectin represents an attractive biomarker that could be utilized in various gastrointestinal (GI) diseases apart from IBD, including IBS, microscopic colitis, acute gastroenteritis, Clostridium difficile infection, colorectal cancer, diverticular disease, and coeliac disease 3.
- Serum calprotectin levels have been studied as a potential inflammatory marker for IBD, with higher levels found in patients with Crohn's disease (CD) and ulcerative colitis (UC) compared to healthy controls 4, 5.
Pediatric Inflammatory Bowel Disease
- Fecal calprotectin has been evaluated as a diagnostic tool in pediatric IBD, with studies showing higher levels in patients with IBD compared to healthy controls or those with functional disorders 6.
- The test could be used to support diagnosis or confirm relapse of IBD in pediatric patients, with a positive result confirming suspicion of IBD diagnosis or relapse due to its high sensitivity 6.