From the Guidelines
Fecal calprotectin is a valuable non-invasive biomarker for detecting and monitoring intestinal inflammation in inflammatory bowel diseases (IBD), with levels above 150 μg/g suggesting active inflammation. The test measures the level of calprotectin, a protein released by neutrophils during inflammation, in stool samples. According to the most recent guideline from the American Gastroenterological Association (AGA) in 2023 1, fecal calprotectin >150 mg/g can be used to rule in active inflammation and inform treatment adjustment in patients with moderate to severe symptoms.
Key Points
- Fecal calprotectin is a useful surrogate marker of inflammatory activity in IBD, correlating well with endoscopic inflammation in ulcerative colitis and Crohn’s disease 1.
- A fecal calprotectin cut-off of 50 μg/g has a high sensitivity (90.6%) for detecting endoscopically active disease, while a threshold of 250 μg/g provides better specificity (82%) for differentiating active IBD from remission 1.
- The AGA suggests using fecal calprotectin >150 mg/g or CRP >5 mg/L to rule in active inflammation and inform treatment adjustment in patients with moderate to severe symptoms 1.
- Fecal calprotectin levels can fluctuate with disease activity, making it useful for predicting flares and adjusting treatment plans before symptoms worsen.
Clinical Application
In clinical practice, fecal calprotectin can be used to distinguish between IBD and irritable bowel syndrome (IBS), as elevated levels indicate organic inflammation rather than functional disorders. It is particularly valuable for monitoring disease activity and treatment response in IBD patients, potentially reducing the need for invasive procedures like colonoscopies. However, other conditions like gastrointestinal infections, certain medications (particularly NSAIDs), and some cancers can also elevate fecal calprotectin, so results should be interpreted within the clinical context 1.
From the Research
Uses of Fecal Calprotectin
- Fecal calprotectin (FC) is a non-invasive marker of gastrointestinal inflammation, used to distinguish between inflammatory bowel disease (IBD) and non-IBD diagnoses 2, 3, 4.
- FC is useful in screening and monitoring IBD, as well as in the differential diagnosis between IBD and irritable bowel syndrome (IBS) 2, 4, 5.
- FC levels correlate with intestinal inflammation, and have been shown to predict relapses and detect pouchitis in patients with IBD 4.
- FC can be used to determine whether clinical symptoms in patients with known IBD are caused by disease flares or non-inflammatory complications/underlying IBS 4.
- FC is also useful in assessing response to treatment and in monitoring disease activity in patients with IBD 5, 6.
- A low FC concentration predicts persistence of clinical remission, especially in non-symptomatic ulcerative colitis and Crohn's colitis 5.
- FC levels have been shown to correlate with endoscopic activity of IBD, and can be used as a predictor for relapse or treatment response 6.
Clinical Applications
- FC can be used as a selection tool for small bowel capsule endoscopy in suspected IBD with prior negative bi-directional endoscopy 3.
- FC >100 μg/g is a good predictor of positive small bowel capsule endoscopy findings, while FC >200 μg/g is associated with higher yield and confirmed Crohn's disease in 50% of cases 3.
- FC can be used to assess inflammatory bowel disease activity, with a strong correlation between FC levels and clinical activity indices 6.
- A cutoff value of 201.3 μg/g for FC-ELISA and 150.5 μg/g for FC-QPOCT can predict endoscopic inflammation in ulcerative colitis with high sensitivity and specificity 6.