Inflammation markers in Crohn's disease and ulcerative colitis

In chronic inflammatory bowel disease, inflammatory markers such as the C-reactive protein (CRP) and the fecal calprotectin from diagnosis to monitoring the course of the disease. Nevertheless, the laboratory markers mentioned can be used to diagnose IBD Not ruled out with certainty or proven can be detected. In addition, CRP values do not allow any clear conclusions to be drawn about disease activity, but can be used in individual cases for Therapy monitoring can be helpful. In this article you can find out more about the laboratory markers CRP and calprotectin.

The reason for this is that both the calprotectin value and the CRP value are not only elevated in the case of IBD, but also as a result of other diseases can be elevated. For example, the calprotectin value can also be elevated in coeliac disease, infectious gastroenteritis or colorectal carcinomas and the CRP value in various viral or bacterial diseases. However, if IBD has been reliably diagnosed, the values for Assessment of inflammatory activity and thus to the Therapy monitoring be helpful. Especially as these non-invasive, fast and comparatively simple can be measured, they are well suited for monitoring the progress of IBD - even if a colonoscopy is not possible.

C-reactive protein (CRP) is a plasma protein that is involved in both acute and chronic inflammatory processes in the body. Liver formed and into Blood is released. As an increase in the CRP value is not only indicative of IBD, but can be elevated in any form of inflammation in the body, it cannot be used as a clear sign of a change in IBD. Other inflammations in the body can be caused by  viral or bacterial disease can also be the case with injuries. The CRP value basically indicates inflammation throughout the body. Nevertheless, testing the C-reactive protein (CRP) in the blood can help to assess inflammatory activity. 

While the CRP value rises in most patients with active Crohn's disease, in some cases there is little or no increase in active ulcerative colitis, and the reason for this correlation between the CRP value in Crohn's disease and the CRP value in ulcerative colitis has not yet been established. The CRP value cannot increase in Crohn's disease patients because it depends on the individual production capacity in the liver. This means that the value can vary from person to person, as a lot or little CRP is produced depending on the individual's production capacity. For these very reasons, it is particularly interesting to monitor CRP levels to assess the course of the disease. In summary, however, the value allows no reliable conclusion on the disease activity, but can be helpful in individual cases.

Calprotectin is a protein that is found, among other things, in Stool samples is found. The concentration of calprotectin in the stool represents the migration of neutrophils through the inflamed intestinal wall into the intestinal cavity. As the sample material is specific to the gastrointestinal tract, elevated calprotectin values can provide information about inflammation specifically in the intestine. In addition, an elevated value before the onset of symptoms can indicate a potentially imminent surge point out. As calprotectin also over several days is detectable in the stool, this parameter is suitable for clinical routine and thus represents a Non-invasive method for therapy monitoring represent. 

Calprotectin & CRP - significance for therapy

Marker	Standard value	Mildly increased	Indication of active inflammation
CRP (C-reactive protein)	< 5 mg/L	5-10 mg/L	> 10 mg/L
Calprotectin (stool)	< 50 µg/g	50-150 µg/g	> 150-250 µg/g (borderline)> 250 µg/g (high)

According to the current S3 guideline, biochemical markers such as CRP and/or faecal calprotectin should be used early - within the first three months of starting or switching therapy - to assess the response to therapy. They complement clinical parameters and imaging procedures such as intestinal sonography.

According to a meta-analysis, a fecal calprotectin value below 50 µg/g is a strong indication against small bowel involvement in Crohn's disease. Calprotectin provides valuable information, particularly in the follow-up diagnosis of symptom-free patients:

• Even without clinical symptoms, an elevated calprotectin level can indicate impending disease activity.
  
• Studies show: The risk of relapse with an elevated value is 53-83 % within 23 months.
  
• If calprotectin is within the normal range, the probability of a sustained remission is 67-94 %.
  

A rising calprotectin value should therefore be taken seriously even in clinical remission and can lead to closer monitoring, an early endoscopic check-up or an adjustment of therapy.

After starting or changing therapy, biochemical markers such as CRP and/or fecal calprotectin as well as intestinal sonography should be used to evaluate the response to therapy within the first three months in addition to clinical parameters.

In summary, laboratory markers such as C-reactive protein (CRP) and fecal calprotectin can be used from diagnosis to treatment. Disease monitoring can help the Inflammatory activity to be assessed. Nevertheless, these laboratory markers cannot reliably rule out or prove the presence of IBD. Nevertheless, in combination with the occurrence of symptoms and other vital parameters such as the Heart rate variability (HRV) can serve as a guide. It is important to always compare the values with the previous coursethe current symptoms and the individual state of mind with your gastroenterologist or gastroenterologist.

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