Inflammatory bowel disease (IBD) represents a spectrum of chronic disorders that affect the gastrointestinal (GI) tract. Crohn disease (CD) and ulcerative colitis (UC) are the major IBD disorders. Fecal calprotectin is a marker of gut inflammation with good sensitivity for detecting IBD. Fecal lactoferrin, an iron-binding protein, is another useful marker of intestinal inflammation in IBD, but more clinical evidence is available for fecal calprotectin.
- Calprotectin is a calcium-binding protein and accounts for 60% of soluble protein in neutrophils
- Calprotectin concentration in feces is proportional to the level of inflammation in patients with UC ; the relationship is more variable in patients with CD
- Calprotectin is stable in stool samples
- IBD symptoms may be vague and similar to those of irritable bowel syndrome (IBS) (eg, diarrhea, abdominal pain)
- IBS is much more prevalent than IBD
- Differentiation of IBD from IBS may require invasive procedures
- Calprotectin testing may be useful as a screen for differentiating IBS and IBD, reducing the necessity of invasive procedures
- Monitoring by endoscopy is invasive
- Calprotectin measurement can be used to help differentiate quiescent from active IBD
- Mucosal healing is associated with sustained remission and is the goal of IBD treatment
- Calprotectin levels correlate with endoscopic scoring systems that are used to assess mucosal healing and may be useful in evaluating mucosal healing
Screening performance for IBD
- Sensitivity: 93% in adults; 92% in children
- Specificity: 96% in adults; 76% in children
- More sensitive and specific than serum inflammatory markers
- Individuals with high pretest probability of IBD (>75%) should be referred directly to endoscopy due to the risk of false-negative calprotectin results
- Screening for elevated fecal calprotectin in individuals with low pretest probability for IBD may result in cost savings by reducing need for unnecessary procedures
- Confirm positive results by endoscopy and follow negative result clinically
Likely to rule out IBD in adults with <75% prior probability
Reevaluation in 4-6 weeks is recommended
Supports diagnosis of IBD
- Calprotectin is not specific for IBD and is also elevated in:
- GI infections
- Colorectal cancer
- Celiac disease
- Mild elevations may be seen with nonsteroidal anti-inflammatory drug or aspirin use
- Calprotectin concentration alone is not diagnostic for IBD
- Calprotectin does not distinguish celiac disease from UC
- Results may fluctuate as disease activity fluctuates
- GI bleeding can cause mild increases in fecal calprotectin concentrations
- Concentrations of fecal biomarkers may vary in different stool samples from a single patient
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