Calprotectin is a 24 kDa dimer of calcium binding proteins S100A8 and S100A9.The complex accounts for up to 60% of the soluble protein content of the neutrophil cytosol.Calprotectin becomes available in the intestinal lumen via leukocyte shedding,active secretion,cell disturbance, and cell death.This results in elevated faecal calprotectin levels, which can be detected in the stool.Elevated faecal calprotectin levels therefore indicate migration of neutrophils into the intestinal mucosa, which occurs during intestinal inflammation.Faecal calprotectin has been used to detect intestinal inflammation, and can serve as a marker for inflammatory bowel diseases.Calprotectin is useful as a marker, as it is resistant to enzymatic degradation, and can be easily measured in faeces.