Part 2: What does having positive calprotectin mean?

Calprotectin is an abundant protein in the organism that comes from leucocytes (white blood cells). That is, it is a substance produced in the immune system cells which helps the body fight off infections and diseases. When there is inflammation in the gastrointestinal (GI) tract, neutrophils move to the inflamed area and that is when they liberate the calprotectin. A posteriori, those proteins will be eliminated along with other residues as stool. The fecal, in the stool, concentration of calprotectin is about 6 times higher compared to the levels of it in blood. 

The stool, when it is examined under the microscope in the laboratory, will show levels of positive calprotectin. As a general rule, high levels of calprotectin indicate bacterial or parasitic infections, colorectal cancer or certain diseases that cause intestinal inflammation, such as ulcerative colitis and Crohn’s disease. In those latter cases, the higher the calprotectin, the more severe the inflammation. However, fecal calprotectin does not indicate the location or the cause of the gastrointestinal inflammation. In order to determinate the cause, signs and symptoms of the inflammation a colonoscopy can be required. 

Low levels of calprotectin indicate that the signs and symptoms are attributable to a different cause (non-inflammatory). That is the case for irritable bowel syndrome and viral infections. Precisely, it is common for doctors to find it difficult to differentiate between an irritable bowel syndrome (IBS) and an inflammatory bowel disease. That happens because sometimes symptoms are practically the same (diarrhea and abdominal pain) for both diseases.  Fecal calprotectin comes into play here: this biomarker will show higher levels in IBD patients than in those suffering from IBS.

Positive calprotectin in the IBD monitoring

Those who join the growing tendency to base the treatment of inflammatory bowel disease on objective data, propose to identify biomarkers that allow selecting those patients who will benefit more from an endoscopic examination. The fecal calprotectin has been proposed here as a biomarker for the bowel inflammation. It allows differentiating the IBD, it has a better correlation with the degree of inflammation than clinical indices and serological markers, and could be useful for predicting mucosal healing and risk of relapse. Because, with the measurement of calprotectin in stool repeatedly, changes can be monitored at the intestinal level of a patient for a long period of time.

Relapsing means experiencing the disease again shortly after finishing the convalescence of it. IBD is characterized by periods of activity remission, with corresponding relapses when the inflammation increases again. This situation is difficult to predict. It is usually done with patient’s monitoring to explore symptoms, although this is not fully effective. The signs may appear after the inflammation of the mucosa; therefore, it does not serve to detect relapses. 

The fecal calprotectin is said to be more useful to discover the risk of relapsing. Since, the increase1 in calprotectin occurs three months before experiencing the disease again after an effective treatment. This can serve to foresee the risk (although, in some occasions, this increase just implies activity without symptoms). 

What is necessary for the realization of a fecal calprotectin? 

In order to detect fecal calprotectin, just take a stool sample and put it in a container.  The test can be reliably analyzed on a sample of less than 5 grams, although it is recommended for the collected sample to be larger. It is a normal collection that does not require any particular care. It is the same process as for a routine urine test; it is advisable to take the sample with the first deposition of the day. It can be stored for three days maximum before taking it to the corresponding specialist for it to be analyzed.

It is not recommended to administer treatments such as suppositories or enemas within 24 hours prior to the collection of the sample. Neither is to take anti-inflammatory drugs within the previous days. And lastly: if there is a scheduled colonoscopy, the collection cannot be done until three days after the test.
1 https://www.elsevier.com/es-es/connect/educacion-medica/niveles-de-calprotectina-fecal,-claves-para-el-diagnostico-y-tratamiento-de-la-eii-conclusiones-del-ii-elsevieraegtalks


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