From the Guidelines
Fecal calprotectin is a highly useful biomarker for diagnosing and monitoring inflammatory bowel disease (IBD), with a threshold of 150 μg/g providing a good balance between sensitivity and specificity for detecting endoscopically active disease 1. When interpreting fecal calprotectin results, it is essential to consider the clinical context and symptoms of the patient. The test measures calprotectin, a protein released by neutrophils during inflammation, in stool samples. Normal levels are typically below 50 μg/g, with values between 50-150 μg/g considered borderline, and values above 150 μg/g suggesting active inflammation. To use this test effectively, patients should collect a small stool sample following the collection kit instructions, avoiding NSAIDs, aspirin, and proton pump inhibitors for 2-4 weeks before testing as these can elevate results. The test is particularly useful for monitoring IBD disease activity, guiding treatment decisions, predicting relapse, and reducing the need for invasive procedures like colonoscopy. It's especially valuable in pediatric patients where minimizing radiation exposure and invasive procedures is important. However, results should be interpreted alongside clinical symptoms and other diagnostic findings, as elevated levels can occur in other conditions like infections, certain cancers, or with medication use. In patients with UC in symptomatic remission, a biomarker- and symptom-based monitoring strategy is suggested, using fecal calprotectin <150 mg/g to rule out active inflammation and avoid routine endoscopic assessment of disease 1. For patients with moderate to severe symptoms, fecal calprotectin >150 mg/g can inform treatment decisions and avoid routine endoscopic assessment of disease. Key considerations for optimal use of biomarkers include patient education, test result interpretation, and integration with clinical symptoms and other diagnostic findings. In clinical practice, the use of fecal calprotectin as a non-invasive alternative to flexible sigmoidoscopy or colonoscopy and cross-sectional imaging is recommended when it is unclear whether new symptoms represent a relapse or other causes, particularly in Crohn’s disease 1.
From the Research
Clinical Utility of Fecal Calprotectin in Diagnosing IBD
- Fecal calprotectin (FC) has emerged as a useful tool for clinical management of inflammatory bowel diseases (IBD) 2, 3, 4, 5, 6.
- FC can reliably differentiate between IBD and irritable bowel syndrome (IBS) due to its high negative predictive value, allowing for the exclusion of active IBD in patients with normal FC levels 2, 3, 5, 6.
- The optimal cut-off for differentiating IBD from IBS is still a concern, with suggested cut-offs ranging from 50 μg/g to 250 μg/g 5.
Monitoring Disease Activity and Response to Therapy
- FC correlates closely with endoscopic activity of IBD and can be used to monitor disease activity and response to therapy 3, 4, 6.
- Elevated FC levels in patients with clinical remission are associated with an increased risk of disease relapse within 12 months of follow-up 3.
- FC can detect subclinical mucosal inflammation, identifying patients at risk for relapse 3.
- A low FC concentration predicts persistence of clinical remission, especially in non-symptomatic ulcerative colitis and Crohn's colitis 4.
Advantages and Stability of Fecal Calprotectin
- FC measurement represents a cheap, safe, and reliable test that is easy to perform and has good reproducibility 2.
- FC is stable once extracted and frozen for up to 2.5 months, and different ELISA kits have been shown to be broadly comparable 5.
- The use of FC in a treat-to-target approach has led to better outcomes than clinically-based therapy adjustment in patients with early Crohn's disease 2.