faecal calprotectin and faecal immunochemical testing
When to test faecal calprotectin
FCP is used primarily to differentiate IBS from IBD in adults with symptoms consistent with IBS.1 However, access to FCP testing in primary care is variable, with around 66% of GP practices using it.2 Some regions across the UK may commission testing differently, including reference ranges and thresholds for referral. Testing should follow the national Primary Care Diagnostic Pathway for Lower-GI Symptoms in conjunction with local best practice.
Before diagnosing IBS, think ‘could this be IBD?’
Interpreting faecal calprotectin
Negative FCP results can confidently exclude IBD in patients with low pre-test risk. However, not all patients with IBD have significantly raised FCP. FCP results should be interpreted alongside clinical features, and persistent, evolving or concerning symptoms should prompt reassessment or referral regardless of result.
Results should be interpreted in line with local laboratory and commissioning guidance. Recent NSAIDs/PPIs/SSRIs/metformin, antibiotics and travel/infective exposure can mimic or confound inflammatory presentations and should be reviewed.
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Who have lower-GI symptoms
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Who have had a negative FIT
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In whom colorectal cancer is not suspected.
This reflects the recognised second peak of IBD incidence in later life. Results should be interpreted cautiously in this age group, as mild elevations are more common and may relate to comorbidity or medication use.5
Great caution should be exercised in interpreting results outside the intended use of excluding IBD in suspected IBS. Positive FCP results should be interpreted with caution,6 as raised FCP does not automatically indicate IBD.
Other causes of raised FCP include:7
GI infections
Colorectal or gastric cancer
Excessive alcohol
Microscopic colitis8
GI ulcers
Diverticulitis
Coeliac disease
Malabsorption syndromes9
Drug-induced enteropathy (e.g. NSAIDs, PPIs or aspirin)10
Obesity11
Faecal immunochemical testing
In primary care, FIT is used in suspicion of colorectal cancer, including when a screening FIT test has recently come back negative.12 FIT should not be used when cancer is not suspected or FCP is being considering instead.
The cut-off for FIT screening is 120u/g in England and Northern Ireland and 80u/g In Scotland and Wales,13 while the cut-off for symptomatic FIT is 10u/g in England, Northern Ireland and Wales and 20u/g in Scotland.14
KNOWLEDGE CHECK
Question 1/3
What is the main use of FCP in primary care?
click for REFERENCES
A digital learning tool designed to support primary care professionals in diagnosing lower-gastrointestinal symptoms using the national pathway.
