Update on clinical and research application of fecal biomarkers for gastrointestinal diseases

Table 1 Fecal biomarkers for gastrointestinal diseases in clinical use with established diagnostic accuracies

S#	Name	Indication	Limitations	Sensitivity	Specificity
Biomarkers of IBD
1	Calprotectin	Distinguishing functional from organic bowel disease and predicting relapse in IBD	Disease nonspecific Affected by age, comorbidities, NSAIDs use Day to day variations Miss low level inflammatory activity	70%-100%	70%-100%
2	S100 proteins	Inflammatory marker for IBD		60%-67%	70%-90%
3	Lactoferrin	Markers of inflammation, Distinguish between IBS and IBD	Nonspecific marker of inflammation Raised in breastfeeding infants Cannot predict low level inflammation	67%-87%	90%-100%
Biomarker of cell turnover
4	M2-PK	Screening of gastrointestinal tract cancers	Also raised in inflammation	67%-93%	88%-92%
Biomarkers of digestion and malabsorption
5	Elastase-1 (e1)	Pancreatic insufficiency	Low specificity, also affected by other intestinal disorders	100%	96%
6	Fecal fat	Liver damage, hypolipidemic drugs, impaired gallbladder function, Celiac disease, Small bowel bacterial overgrowth	Cannot predict severity of disease Cannot be performed in diarrhea Not accurate or specific test	70%-94%	80%-99%
7	Α1-antitrypsin	Protein-Losing Enteropathy, Whipple lipodystrophy, gastric carcinoma, intestinal lymphangiectasia	Nonspecific marker. Levels affected by inflammation	60%-78%	80%-85%

IBD: Inflammatory bowel disease; IBS: Irritable bowel syndrome; NSAID: Nonsteroidal anti-inflammatory drug.