Background and aims: Calprotectin and lactoferrin are specific neutrophil-derived proteins, which can be measured in the feces because they are released by cells in inflammatory conditions. We evaluated the efficacy of calprotectin and lactoferrin in detecting organic disease as assessed by colonoscopy.
Methods: The study comprised 144 patients undergoing colonoscopy for lower gastrointestinal symptoms (abdominal pain, altered bowel habits, and bloody stools) (67), or inflammatory bowel disease activity, or surveillance for dysplasia (77). A single stool sample was assayed for calprotectin and lactoferrin. The proportion of patients correctly diagnosed with each test and the relationship with endoscopic and histological findings were measured.
Results: Fecal excretion of calprotectin significantly correlated with the finding of colonic inflammation at endoscopy, both in ulcerative colitis and in Crohn's disease (p<0,001 and p<0,008, respectively), while lactoferrin excretion significantly correlated with histological inflammation (p=0.001 and p=0.009 respectively). Recommended cut-off values need to be adjusted in the inflammatory bowel disease group. Overall sensitivity, specificity, positive predictive value, and diagnostic efficacy were 78, 83, 86, and 80% for calprotectin and 80, 85, 87, and 81% for lactoferrin, respectively.
Conclusions: Fecal calprotectin and lactoferrin appear to be equally recommendable as inflammatory disease markers in patients with lower gastrointestinal symptoms. Both tests are needed to accurately discriminate activity in inflammatory bowel disease patients.