Faecal Calprotectin

💩🧪 Faecal calprotectin is a stool test used to help distinguish Irritable Bowel Syndrome (IBS) from Inflammatory Bowel Disease (IBD) when symptoms overlap and there is diagnostic uncertainty.

🚦 High levels suggest intestinal inflammation - but they do not diagnose IBD on their own.

🎯 When to Use

• ✅ Adults with lower gastrointestinal symptoms where IBS vs IBD is uncertain.
• ✅ Suspected IBD where symptoms are mild/moderate and there are no red flags.
• ✅ Diarrhoea-predominant or mixed-type IBS symptoms where inflammatory disease needs excluding.
• ❌ Do not use as a substitute for urgent referral if colorectal cancer is suspected.
• ❌ Do not delay urgent assessment if acute severe IBD is suspected.
• ⚠️ If ovarian cancer symptoms are suspected, consider CA125 and appropriate pelvic/abdominal assessment.

🚩 Red Flags - Do Not Rely on Calprotectin Alone

• 🩸 Rectal bleeding
• ⚖️ Unexplained weight loss
• 😴 Iron deficiency anaemia or unexplained anaemia
• 👆 Abdominal or rectal mass
• 👵 New change in bowel habit in older adults
• 🧬 Strong family history of bowel or ovarian cancer
• 🔥 Severe abdominal pain, systemic toxicity, dehydration, or suspected acute severe colitis

🧬 What Is Calprotectin?

• Calprotectin is a protein found mainly inside neutrophils 🧫.
• When the bowel lining is inflamed, neutrophils migrate into the gut wall and release calprotectin into the stool.
• Because it is stable in faeces, it is a useful marker of intestinal inflammation.
• IBS is a functional gut disorder and usually does not cause a high faecal calprotectin.

📈 Causes of Raised Faecal Calprotectin

• 🔥 Inflammatory bowel disease - Crohn’s disease or ulcerative colitis
• 🦠 Infective colitis or gastroenteritis
• 🧱 Diverticulitis
• 💊 Medicines, especially NSAIDs
• 🧬 Colorectal cancer or other bowel pathology
• 🚑 Recent gastrointestinal bleeding, inflammation, or surgery

💊 Medication Cautions

• NSAIDs such as ibuprofen, naproxen and aspirin can increase faecal calprotectin.
• If clinically safe, avoid NSAIDs before testing according to local laboratory guidance.
• Do not stop aspirin or antiplatelet therapy without considering the cardiovascular indication.
• Recent infection can also raise levels, so repeat testing may be needed if symptoms are settling.

🚦 Interpreting Results

• 🟢 <100 micrograms/g: IBD unlikely.
  • Manage as likely IBS if the clinical picture fits.
  • Give lifestyle, diet and symptom-directed treatment.
  • Review if symptoms persist, worsen, or red flags develop.
• 🟠 100–250 micrograms/g: Borderline / intermediate result.
  • Check for NSAID use, infection, recent gastroenteritis and other inflammatory causes.
  • Repeat faecal calprotectin, often within around 4 weeks depending on local pathway.
  • If persistently raised, consider routine gastroenterology referral or advice and guidance.
• 🔴 >250 micrograms/g: Significant intestinal inflammation more likely.
  • Review clinically and check for red flags or systemic illness.
  • Consider urgent gastroenterology referral, especially if symptoms are worsening.
  • Repeat testing may be used to confirm elevation if the patient is clinically stable.

🧠 Simple Exam Pearl

• 💡 IBS: symptoms without objective bowel inflammation - calprotectin usually normal.
• 🔥 IBD: immune-mediated bowel inflammation - calprotectin often raised.
• ⚠️ Raised calprotectin means inflammation, not automatically IBD.

📦 Sample Requirements

• Collect approximately 1–5 g of faeces into a stool collection pot.
• Avoid contamination with urine or toilet water.
• Label the sample clearly and send according to local laboratory instructions.
• Local laboratories may use different thresholds, so always interpret using the local reference range.

🗣️ Advice for Patients

• 💩 The test looks for inflammation in the bowel, not infection alone and not cancer specifically.
• 📦 A small stool sample is enough.
• 💊 Tell the clinician about NSAIDs, aspirin, recent diarrhoea, antibiotics or infections.
• 🚩 Seek urgent medical advice if there is rectal bleeding, weight loss, severe pain, fever, dehydration, or black stools.
• 📄 How to collect a stool sample for faecal calprotectin analysis

📚 Terminology

• IBS: Irritable Bowel Syndrome - functional bowel symptoms without structural inflammation.
• IBD: Inflammatory Bowel Disease - chronic inflammatory disease such as Crohn’s disease or ulcerative colitis.
• FC: Faecal calprotectin.