What is Fecal Calprotectin?

Calprotectin is an inflammatory protein abundantly present in neutrophils, and also, a calcium binding protein which is released from migrant neutrophils after infiltering to the intestinal mucosa [*1]. The amount of calprotectin in feces increases accompanied with intestinal mucosal inflammation. Therefore, measuring the amount of calprotectin in feces can be used for disease monitoring of inflammatory bowel disease (IBD) patients and distinguishing IBD (e.g. ulcerative colitis, Crohn’s disease) from functional intestinal disorders (IBS; e.g. irritable bowel syndrome) [*2-5].

• NICE Guidance (DG11) in the U.K., fecal calprotectin is recommended as “an option to support clinicians with the differential diagnosis of IBD or IBS [*6]".
• American College of Gastroenterology (ACG) strongly recommends fecal Calprotectin as “a helpful test that should be considered to help differentiate the presence of IBD from IBS [*7]”. 
• European Crohn’s and Colitis Organisation (ECCO) also published the guideline and mentioned about fecal calprotectin: “Calprotectin values correlate well with endoscopic indices of disease activity and are thus important in various clinical settings, including initial diagnosis, diagnosis of relapse, and response to treatment [*8]”. 

Manufacturers are set the threshold at 50μg/g (mg/kg) commonly as the marker of the distinguishing IBD from functional intestinal disorders [*6]. 

• The study about diagnostic accuracies of fecal hemoglobin (FHb) and fecal calprotectin (FC) was conducted in a cohort of symptomatic patients in the U.K.
• Their data indicates that the possibility of utilities on testing FHb and FC simultaneously for predicting the absence of significant bowel disease (cancer, higher-risk adenoma or IBD ) in primary care as follows; “The negative predictive values of FHb for colorectal cancer, higher-risk adenoma and IBD were 100%, 97.8% and 98.4%, respectively. Using cut-offs of detectable FHb and/or 200 mg/g FC detected two further cases of IBD, one higher-risk adenoma and no additional cancers [*9].” 

1. Burri et al., Faecal Calprotectin in the Diagnosis of Inflammatory Bowel Disease, Biochemia Medica, 2011; 21(3): 245-53.
2. Tibble et al., A simple method for assessing intestinal inflammation in Crohn's disease, Gut, 47: 506-513, 2000.
3. Tibble et al., Use of surrogate markers of inflammation and Rome criteria to distinguish organic from nonorganic intestinal disease, Gastroenterology, 123: 450-460, 2002.
4. Montalto et al., Fecal calprotectin in first-degree relatives of patients with ulcerative colitis, The American Journal of Gastroenterology, 102: 132-136, 2007.
5. Schoepfer et al., Fecal calprotectin correlates more closely with the Simple Endoscopic Score for Crohn's disease (SES-CD) than CRP, blood leukocytes, and the CDAI, The American Journal of Gastroenterology, 105: 162-169, 2010.
6. National Institute for Health and Care Excellence. NICE Diagnostics guidance DG11. Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel. https://www.nice.org.uk/guidance/dg11 Published 2013. 
7. Lichtenstein et al., ACG clinical guideline: management of Crohn’s disease in adults. Am J Gastroenterol. 2018;113:481–517.
8. Masser et al., ECCO-ESGAR Guideline for Diagnostic Assessment in IBD Part 1: Initial diagnosis, monitoring of known IBD, detection of complications, Journal of Cron’s and Colitis, 2019, 144–165K.
9. Mowat et al., Faecal haemoglobin and faecal calprotectin as indicators of bowel disease in patients presenting to primary care with bowel symptoms, Gut 2015;0:1–7.