Prospective Evaluation of Faecal Neutrophil-derived Proteins in Identifying Intestinal Inflammation: Combination of Parameters Does Not Improve Diagnostic Accuracy of Calprotectin

Background: Differentiating symptoms of irritable bowel syndrome from those of organic intestinal disease is a common clinical problem. Several neutrophil-derived proteins have been proposed as a marker of inflammatory bowel disease.

Aim: To compare the diagnostic value of faecal calprotectin, lactoferrin and polymorphonuclear neutrophil-elastase in distinguishing inflammatory bowel disease from irritable bowel syndrome.

Methods: Eighty-eight adult patients with a history of chronic diarrhoea of unknown origin were screened. All patients underwent a complete work-up to identify the underlying cause. In addition, a single stool sample was assayed for faecal calprotectin, lactoferrin and polymorphonuclear neutrophil-elastase by enzyme-linked immunosorbent assay.

Results: Within the study cohort inflammatory bowel disease was diagnosed in 45 patients and irritable bowel syndrome in 31 patients. The sensitivity and specificity of calprotectin for inflammatory bowel disease were 93% and 100%, respectively. In contrast, the respective diagnostic values for lactoferrin and polymorphonuclear neutrophil-elastase were 82% and 100% and 84% and 87%, respectively. Neither combination of markers did improve the diagnostic power compared with calprotectin alone.

Conclusions: Although all faecal biomarkers studied provide a reliable and simple non-invasive means in the differentiation of inflammatory bowel disease and irritable bowel syndrome, calprotectin appears to represent the most accurate marker to discriminate between these two common causes of chronic diarrhoea.