| Faecal marker | Function | Main source | Differentiating IBD from IBS | Correlation* to IBD activity† | Stability at RT |
| S100A8/S100A9 (Calprotectin) | DAMP | Neutrophils (cytoplasm), monocytes, epithelium | + | ++ | 7 days12 |
| S100A12 | DAMP | Neutrophils (cytoplasm) | + | ++ | >7 days13 |
| Lactoferrin | Leukocyte degranulation marker | Brush-border cells, neutrophils, monocytes, macrophages, lymphocytes | + | + | 4 days14 |
| Polymorphonuclear elastase | Leukocyte degranulation marker | Neutrophils (azurophilic granules) | ND | ++ | 1 day15 |
| α1-Antitrypsin | Marker of protein loss | Hepatocytes, epithelium | ND | + | 7 days16 |
| Tumour necrosis factor α | Cytokine | Monocytes, macrophages, T cells | ND | (+) | Not stable17 18 |
| Eosinophil cationic protein | Leukocyte degranulation marker | Eosinophils (specific granules) | ND | − | 3 days19 |
| Eosinophilic protein X | Leukocyte degranulation marker | Eosinophils (specific granules) | ND | (+) | 7 days19 |
| Myeloperoxidase | Leukocyte degranulation marker | Neutrophils (azurophilic granules), monocytes, macrophages, T cells | ND | − | 1 day15 |
| Lysozyme | Leukocyte degranulation marker | Neutrophils (azurophilic granules), macrophages, epithelium | ND | + | 1 day15 |
| Faecal occult blood | Marker of blood loss | Erythrocytes (haemoglobulin; mucosal damage) | ND | − | Stable |
*Significance: −, all studies negative; (+), some studies positive; +, most studies positive (some not in both Crohn’s disease and ulcerative colitis); ++, all studies positive.
†Disease activity measures depending on study definition: Classification of active/inactive disease; CDAI/CAI; endoscopy; histology.
CAI, colitis activity index; CDAI, Crohn’s disease activity index; DAMP, damage-associated molecular pattern; IBD, inflammatory bowel disease; IBS, inflammatory bowel syndrome; ND, not determined; RT, room temperature.