Gastroenterology is the medical specialty involved in the diagnosis, treatment and monitoring of diseases of the entire digestive system, metabolism and nutrition. Depending on the pathology, various biomarkers of gastrointestinal inflammation can be measured to aid diagnosis. Diseases of the digestive system affect one in five people in France and are the main reason for admission to hospital.

Distinguishing IBD from functional syndromes

Crohn’s disease is a chronic inflammatory bowel disease (IBD). Calprotectin is a very specific biomarker of gastrointestinal inflammation. Its measurement allows the differentiation of IBD (Crohn’s disease, hemorrhagic rectocolitis, coeliac disease…) from functional syndromes (irritable bowel for example). A value of more than 50 mg/kg will lead to further diagnostic investigations, particularly endoscopic ones. Calprotectin is used for diagnosis and also for monitoring the disease.

The clearance of fecal alpha-1-antitrypsin is an indicator of intestinal protein loss (ulcerative colitis, Crohn’s disease) and therefore a marker of choice for assessing the intensity and activity of inflammatory bowel diseases.  Indeed, alpha-1-antitrypsin is synthesized in the liver, not degraded in the digestive tract and therefore excreted almost intact in the stool.

Celiac disease

Patients with celiac disease or gluten intolerance are 5 to 10 times more likely to have a selective IgA deficiency.  Serum IgA concentration should therefore be part of the initial screening prior to the determination of tissue IgA transglutaminases and in particular to identify IgA deficiency.

In the context of non-invasive monitoring of chronic liver diseases, various combinations of biomarkers associated with calculation algorithms make it possible to obtain fibrosis and steatosis scores (FibroTest®, FibroMetre V®, Hepascore).  These biochemical scores involve various protein assays such as alpha-2-macroglobulin, haptoglobin and apolipoprotein A1.