How accurate is calprotectin for diagnosing IBD?

Faecal calprotectin has a high negative predictive value (above 90%) for IBD when results are below 50 µg/g, making it excellent for ruling out organic disease. Elevated values above 150–250 µg/g support referral for colonoscopy but do not confirm IBD, as other causes of intestinal inflammation can also raise calprotectin.

Can calprotectin be elevated without IBD?

Yes. Gastroenteritis, NSAID enteropathy, gastrointestinal infections, colonic neoplasia, diverticulitis, and ischaemic colitis all raise calprotectin. Acute infection should be excluded and NSAIDs discontinued before testing when possible.

Is fasting required for a calprotectin stool test?

No. Patients collect a small stool sample at home in the kit provided; no dietary restriction or fasting is necessary.

How should patients collect the stool sample?

Patients use the sterile collection container supplied by the laboratory, depositing a pea-sized sample (approximately 3–5 g) and avoiding contamination with urine or toilet water. The specimen should be refrigerated if not posted immediately, and detailed instructions are included in the kit.

Can calprotectin replace colonoscopy?

No. Calprotectin is a triage and monitoring tool, not a substitute for endoscopy. Elevated results warrant colonoscopy with biopsy for diagnosis, and endoscopy remains the gold standard for assessing mucosal healing and disease extent.

How is calprotectin used to monitor IBD?

In established Crohn's disease or ulcerative colitis, serial calprotectin tracks mucosal inflammation, guides treatment escalation or de-escalation, and predicts relapse during clinical remission. Trends are more informative than single values and should be integrated with symptoms and endoscopic findings.

Are reference ranges the same for children and adults?

No. Infants and young children have higher baseline calprotectin due to physiological intestinal permeability and microbiome development. Age-adjusted reference intervals must be used, particularly in children under four years.

BML-MBG-010microbiome gutUSA

Calprotectin Stool Test

Q: Why should NSAIDs be stopped before testing?

Non-steroidal anti-inflammatory drugs cause enteropathy and increase intestinal permeability, raising calprotectin in the absence of IBD. A drug-free interval of one to two weeks is recommended when clinically feasible to avoid false-positive results.

The calprotectin stool test quantifies a neutrophil-derived protein in faeces to detect and monitor intestinal inflammation. It distinguishes organic inflammatory bowel disease from functional disorders, guides colonoscopy triage, and tracks mucosal healing and relapse in established IBD as part of treat-to-target strategies.

Biomarkers

Stool

Sample

2–5 business days

Turnaround

Fasting

What is the Faecal Calprotectin test?

The Calprotectin Stool Test quantifies a neutrophil-derived protein in faeces to detect and monitor intestinal inflammation. Practitioners order it as a first-line, non-invasive screen to separate patients with functional symptoms from those who require colonoscopy for suspected inflammatory bowel disease, and as a longitudinal biomarker in known IBD to assess mucosal healing, guide immunosuppressive dose adjustments, and predict relapse. Because calprotectin reflects active neutrophilic inflammation rather than structural change or non-inflammatory pathology, it fills a diagnostic gap between symptom burden and endoscopic or cross-sectional imaging. A result below 50 µg/g carries a high negative predictive value for IBD in new presentations, allowing clinicians to reassure patients and avoid unnecessary colonoscopy. Conversely, persistent elevation above 150–250 µg/g in the appropriate clinical context warrants endoscopic confirmation and biopsy. Serial testing tracks disease activity more reliably than symptoms alone and is now embedded in treat-to-target IBD strategies.

What does the Faecal Calprotectin test measure?

FC(Faecal Calprotectin)

Range: <50 µg/g in adults; age-specific thresholds apply in infants and young children.Optimal: Most guidelines consider <50 µg/g reassuring and >150–250 µg/g (exact threshold varies by assay and clinical context) strongly suggestive of IBD or other organic inflammation.µg/g / mg/kg

Calprotectin is a calcium- and zinc-binding heterocomplex (S100A8/A9) that accounts for roughly half the cytosolic protein content of neutrophils. When neutrophils migrate into the intestinal lumen in response to mucosal inflammation, calprotectin is released and remains stable in stool for several days at room temperature, making it a robust non-invasive marker of intestinal neutrophil infiltration. Faecal concentration reflects the intensity of mucosal inflammatory activity rather than structural damage, so it rises and falls with disease flares and remissions.

Faecal calprotectin is the single most useful stool biomarker for distinguishing organic inflammatory bowel disease from functional gastrointestinal disorders. Elevated levels indicate active intestinal inflammation — most commonly Crohn's disease or ulcerative colitis — and support prioritisation for endoscopy, whereas normal or low values make IBD unlikely and reduce the need for invasive investigation. In patients with established IBD, serial calprotectin guides treatment escalation, monitors response to therapy, and predicts clinical and endoscopic relapse months before symptoms emerge.

Why is the Faecal Calprotectin test ordered?

Initial investigation of chronic diarrhoea, abdominal pain, or blood in stool to distinguish functional from inflammatory disease before referring for colonoscopy
Risk stratification and triage in primary care when IBD is in the differential but resources for endoscopy are limited or the clinical probability is intermediate
Monitoring of established Crohn's disease or ulcerative colitis for mucosal healing, treatment response, and early detection of relapse during clinical remission
Paediatric gastroenterology, where calprotectin has particularly high utility for avoiding invasive procedures in children with functional abdominal symptoms
Post-operative monitoring in Crohn's disease to detect early recurrence of inflammation at the anastomosis site
Exclusion of organic inflammation in irritable bowel syndrome mimics, coeliac disease work-up, and assessment of colitis from other causes (infectious, ischaemic, drug-induced)
Guiding decisions to escalate or de-escalate immunosuppressive or biologic therapy in IBD, interpreted alongside clinical and endoscopic findings
Investigation of unexplained iron-deficiency anaemia or raised inflammatory markers when an intestinal source is suspected

Sample collection and turnaround

Sample type

Stool

Fasting required

Collection method

At-home collection kit

Turnaround

2–5 business days

Collection notes

Patient self-collection using a sterile stool collection container supplied by the laboratory. A small sample (pea-sized, approximately 3–5 g) is typically sufficient. Patients should avoid contamination with urine or toilet water, and the specimen should be refrigerated if not shipped immediately. Detailed kit instructions are included. Avoid collection during or immediately after an acute diarrhoeal illness if possible, and discontinue NSAIDs for one to two weeks before testing when clinically feasible.

Specimen requirements

Minimum 3–5 g of unpreserved stool in the collection vial provided. Calprotectin is stable at room temperature for several days and remains reliable after refrigeration or freezing, though prompt return is preferred. Note the assay platform (Quest or Doctor's Data) for serial comparability.

What can affect Faecal Calprotectin results?

elevatesNon-steroidal anti-inflammatory drugs and aspirin

NSAIDs cause enteropathy and increase intestinal permeability, raising calprotectin in the absence of IBD; a drug-free interval of at least one to two weeks is recommended before testing when feasible.

elevatesGastrointestinal infection

Bacterial, viral, or parasitic gastroenteritis triggers neutrophil infiltration and transiently raises calprotectin; the test should be repeated after resolution of acute infection if initial results are elevated.

elevatesProton-pump inhibitors

PPIs are associated with colonic microscopic inflammation and small increases in calprotectin in some patients, though the magnitude is usually modest and does not preclude interpretation.

elevatesSpecimen contamination with urine or menstrual blood

Urine contains calprotectin; cross-contamination can spuriously raise the result, so collection instructions should emphasise clean technique and avoidance of urinary or menstrual contamination.

elevatesAge (infancy and early childhood)

Physiological intestinal permeability and bacterial colonisation patterns result in higher baseline calprotectin in infants and children under four years; age-adjusted reference intervals must be used.

variableStool consistency and sample handling

Calprotectin is stable at room temperature for several days but may degrade if the specimen is stored improperly or transit is prolonged; very liquid stool can dilute the concentration, though results are normalised to stool weight.

What do Faecal Calprotectin results mean?

Elevated

Inflammatory bowel disease (Crohn's disease, ulcerative colitis) is the most common cause; other organic inflammation including infectious colitis, colonic neoplasia, diverticulitis, ischaemic colitis, and NSAID enteropathy. In established IBD, elevated calprotectin signals active mucosal inflammation and may predict relapse even during clinical remission. Values >250 µg/g carry high specificity for organic disease and warrant endoscopy.

Normal

Normal calprotectin (typically <50 µg/g) makes active IBD unlikely but does not exclude it entirely, particularly in isolated small-bowel Crohn's disease proximal to the terminal ileum or in patients on high-dose corticosteroids. Clinical judgement and correlation with symptoms, imaging, and other inflammatory markers remain essential.

Reduced

Calprotectin <50 µg/g has a high negative predictive value (>90%) for IBD in new presentations, supporting a diagnosis of functional gastrointestinal disorder and reducing the need for invasive investigation. In treated IBD, low calprotectin indicates mucosal healing and is associated with sustained remission.

Note: Calprotectin thresholds differ by assay (ELISA, lateral-flow, chemiluminescence), age, and clinical context; laboratories should specify the method and interval. The test is most informative when pre-test probability of IBD is intermediate (roughly 10–60%); in very high or very low probability settings clinical or endoscopic assessment may be more appropriate. A single elevated result requires correlation with clinical findings and often a repeat sample after excluding infection and NSAID use. In treated IBD, trends matter more than single values, and integration with symptoms and endoscopy is necessary for treatment decisions.

Frequently asked questions

Faecal calprotectin is a neutrophil-derived protein released into the intestinal lumen during mucosal inflammation. Measuring it in stool provides a non-invasive marker of intestinal neutrophil activity, helping to distinguish inflammatory bowel disease from functional disorders and to monitor disease activity in established IBD.

How to access the Faecal Calprotectin test

The Faecal Calprotectin reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.

Create Free Account

About this page

Published: October 7, 2026

Last reviewed: October 7, 2026

References:

Lamb CA, et al. British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults. Gut. (2019)
van Rheenen PF, et al. Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: diagnostic meta-analysis. BMJ. (2010)
Turner D, et al. STRIDE-II: An update on the Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) Initiative of the International Organization for the Study of IBD (IOIBD) — determining therapeutic goals for treat-to-target strategies in IBD. Gastroenterology. (2021)
Mosli MH, et al. C-reactive protein, fecal calprotectin, and stool lactoferrin for detection of endoscopic activity in symptomatic inflammatory bowel disease patients: a systematic review and meta-analysis. Am J Gastroenterol. (2015)
NICE guideline NG12: Suspected cancer — recognition and referral (faecal calprotectin in lower GI symptom triage). (2015)

This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.