A 29-year-old woman has four months of alternating loose stools and constipation with bloating relieved by defecation. CRP is 2 mg/L and haemoglobin is normal. Her faecal calprotectin is 18 micrograms/g (cutoff 50 micrograms/g). How should this result be interpreted?
- A It supports inflammatory bowel disease and mandates immediate colonoscopy
- B It makes active mucosal inflammation unlikely and supports a diagnosis of irritable bowel syndrome ✓
- C It is specific for colorectal malignancy and requires CT colonography
- D It is uninterpretable unless repeated during an acute infective episode
Correct answer: B. It makes active mucosal inflammation unlikely and supports a diagnosis of irritable bowel syndrome
Explanation
Faecal calprotectin is a neutrophil-derived protein released into the lumen during intestinal inflammation. Values below roughly 50 micrograms/g argue strongly against active organic inflammation and support irritable bowel syndrome, allowing invasive workup to be avoided in young patients with typical features and no alarm signs. Elevated values suggest IBD, infection, or neoplasia but are nonspecific. It complements, rather than replaces, endoscopy when alarm features such as weight loss, bleeding, or anaemia are present.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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