Questions and answers on the role of faecal calprotectin as a biological marker in inflammatory bowel disease

Faecal calprotectin has been proposed as a non-invasive surrogate marker of intestinal inflammation in inflammatory bowel disease. Close correlation between faecal calprotectin concentration and faecal leukocyte excretion quantified with ¹¹¹indium has been described. This faecal marker can be detected using simple and cheap techniques. Faecal calprotectin has a good diagnostic precision for separating organic and functional intestinal diseases. However, the specificity for the diagnosis of inflammatory bowel disease is lower than desirable, as several diseases other than inflammatory bowel disease – specially colorectal neoplasia and gastrointestinal infection – can also increase faecal calprotectin. High concentration of calprotectin in faeces is a strong argument to carry out a colonoscopy in order to rule out the presence of inflammatory bowel disease or other organic pathologies. Parallelism between faecal calprotectin levels and inflammatory bowel disease activity has been confirmed, although this faecal marker appears to better reflect the disease activity in ulcerative colitis than in Crohn's disease. Faecal calprotectin's capacity to predict inflammatory bowel diseases relapse is promising. It has been suggested that, in inflammatory bowel disease patients receiving treatment, a normalization or decrease in faecal calprotectin concentrations is an accurate indicator of endoscopic healing. Greater faecal calprotectin concentration has been shown in asymptomatic first-degree relatives of patients with inflammatory bowel disease, suggesting that there is a high prevalence of subclinical intestinal inflammation in them.