From the Guidelines
Fecal calprotectin is a protein found in stool that serves as a biomarker for intestinal inflammation, and its measurement is a useful non-invasive method to investigate patients with chronic gastrointestinal symptoms, particularly in differentiating inflammatory bowel disease (IBD) from irritable bowel syndrome (IBS) 1.
Definition and Use
Fecal calprotectin is released by neutrophils during inflammatory processes in the intestines and correlates well with endoscopic inflammation in both ulcerative colitis (UC) and Crohn’s disease 1. It is commonly used to help diagnose and monitor IBD, and to differentiate these conditions from IBS, which does not cause significant inflammation.
Interpretation of Results
Normal levels are typically below 50 μg/g of stool, with values between 50-150 μg/g considered borderline, and values above 150 μg/g suggesting active inflammation 1. A meta-analysis found that a calprotectin cut-off of 50 μg/g had the best sensitivity (90.6%) to detect endoscopically active disease, while a threshold of 250 μg/g provides better specificity (82%) in differentiating active IBD from remission 1.
Clinical Application
The test is non-invasive, requiring only a small stool sample, making it particularly useful for initial screening and ongoing monitoring of intestinal inflammation 1. It helps clinicians determine whether more invasive procedures like colonoscopy are necessary and assists in evaluating treatment effectiveness for patients with known IBD.
Limitations
However, fecal calprotectin is not sensitive enough to exclude advanced colorectal adenoma or colorectal carcinoma, and thus, in patients with rectal bleeding and abdominal pain, change in bowel habit, weight loss, or iron-deficiency anaemia, cancer pathway referral should be strongly considered 1.
From the Research
Definition of Fecal Calprotectin
- Fecal calprotectin is a protein that can be measured in stool to assess intestinal inflammation 2, 3, 4, 5.
- It is a calcium- and zinc-binding protein of the S-100 protein family, mainly found within neutrophils and throughout the human body 5.
Role of Fecal Calprotectin as a Biomarker
- Fecal calprotectin is considered a promising marker of intestinal inflammation, correlating well with histological inflammation as detected by colonoscopy with biopsies 2, 3, 4.
- It can detect intestinal inflammation and differentiate between organic diseases and functional disorders, such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) 3, 4, 5.
- Fecal calprotectin has been shown to consistently differentiate IBD from IBS, with excellent negative predictive value in ruling out IBD in undiagnosed, symptomatic patients 3.
Clinical Applications of Fecal Calprotectin
- Fecal calprotectin can be used for the diagnosis, monitoring disease activity, treatment guidance, and prediction of disease relapse and post-operative recurrence in IBD 4, 5.
- It may also have a role in the management of infectious gastroenteritis, acute appendicitis, peptic ulcer disease, cystic fibrosis, coeliac disease, transplant rejection, and graft versus host disease, although further studies are needed to confirm its utility in these conditions 5.
- A rapid semi-quantitative calprotectin test can be combined with a symptom index to monitor disease activity in colonic IBD, providing a simple and noninvasive means of distinguishing remission from active inflammation 6.