Calprotectin is a protein of the S100 family, having a structure consisting of one light and two heavy polypeptide chains, with a total molecular weight of 36.5 kDa. It was found present in large quantities in neutrophil granulocytes, where it represents 5% of total proteins and 60% of cytoplasmic proteins. In lesser amounts, calprotectin has also been found in activated monocytes and macrophages.

It is a protein with bacteriostatic and mycostatic activity comparable to that of antibiotics: for this reason, the abundance of calprotectin in the neutrophil granulocytes and its antimicrobial activity suggest an important role in the defensive functions of the organism.

In the presence of inflammatory processes, calprotectin is released following granulation of neutrophil granulocytes. In the case of an inflammation of the intestine, calprotectin can be detected in feces. Fecal dosing is the only one that can provide direct indications on the location of inflammation, while the dosage in serum or plasma shows a state of inflammation that can be present anywhere in the body of the analyzed patient.

The presence of calprotectin has been found in various human biological materials: serum, saliva, cerebrospinal fluid and urine. It is however the dosage of calprotectin present in feces to offer the greatest advantages in the evaluation of the degree of inflammation of the intestine: in fact, the calprotectin is an extremely stable protein in this medium, where it remains unaltered even for more than 7 days.

The increase in calprotectin concentration in feces is a direct consequence of the granulation of neutrophils as a result of mucosal damage. The dosage of calprotectin in stool offers significant advantages in the assessment of bowel inflammation. In patients with chronic intestinal inflammatory diseases, which are internationally known as IBD (Inflammatory Bowel Diseases) and include ulcerative colitis, Crohn's disease and so-called "indeterminate colitis", the level of calprotectin is generally very high. In subjects with Irritable Bowel Syndrome, indicated internationally with IBS, the level of calprotectin is instead much lower than that found in patients with active disease, sometimes higher than the reference limit, but, in any case, always higher than that found in healthy subjects.


Calprest NG and CalFast XT are first level tests for the differential diagnosis between organic and functional bowel pathology and are therefore indicated for all those subjects presenting clinical symptoms common to a large number of gastroenterological functional disorders such as intestinal inflammatory diseases (IBD), irritable bowel syndrome (IBS), diarrhea, recurrent abdominal pain, etc.

Calprest NG and CalFast XT determine the level of calprotectin present in the feces and allow a quick, accurate and quantitative analysis. In addition for being a valid support in the laboratory diagnosis of IBD and IBS, the determination of calprotectin is furthermore a useful tool to monitor the progress of the inflammation and thus the clinical course of the patient, as well as to optimize the treatment of patients suffering from chronic inflammatory bowel diseases.

The tests are carried out in the laboratory on stool samples allowing to determine, through the measurement of the calprotectin concentration, if the subject is affected by IBD (the values​ of calprotectin are decidedly very high) or by IBS: in the latter case the level of calprotectin appears significantly lower than that found in patients with the active disease (IBD), although sometimes it may be slightly higher than that found in healthy subjects.

In healthy adults the average value for calprotectin is about 25 mg calprotectin/kg. If a calprotectin concentration above 50 mg calprotectin/kg is found in the stool sample, the result should be considered positive, therefore it is advisable to proceed with further diagnostic tests to determine the cause of the high protein value.


The determination of fecal calprotectin is as well used in pediatric and neonatal fields.

High levels of fecal calprotectin are also found in pediatric patients with chronic inflammatory bowel diseases (IBD).

In these subjects the sensitivity and specificity of calprotectin determination are more reliable than other biochemical parameters normally used to verify the presence of an inflammatory state affecting the intestine.

In the newborn, which does not yet have a fully developed intestinal function, the introduction of breast milk or food during the first days of life determines an inflammatory response that is accompanied by extremely high levels of calprotectin.

Subsequently these values ​tend to decrease with the normalization of the mucosa. A low or no calprotectin level in the newborn could be due to the presence of other diseases affecting the intestine thus requiring further investigation.