A patient’s story
A few weeks ago, a young professional came to our clinic, worried. They’d been living with bouts of bloating, cramps and unpredictable bowel habits for months. Their GP had mentioned a faecal calprotectin test, but the name alone sounded intimidating.
When the result came back normal, relief quickly turned into confusion: “So what does that actually mean? Do I still need a colonoscopy?”
It’s a familiar question. The faecal calprotectin (FC) test has become one of the most useful, non-invasive tools in modern gut health. Yet many patients aren’t sure how to interpret it. At LSDC Clinic, we use it every week to help decide who needs further investigation, and who can safely avoid it.
What is faecal calprotectin?
Calprotectin is a protein released by white blood cells when there’s inflammation in the lining of the bowel. Measuring its level in a stool sample provides a window into gut inflammation without the need for scopes or imaging.
In simple terms:
Low calprotectin → inflammation unlikely → more consistent with IBS.
- High calprotectin → inflammation likely → possible IBD or another organic cause.
Why it matters
Gastrointestinal symptoms overlap enormously between Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD). Historically, patients with abdominal pain, diarrhoea, or bloating often underwent colonoscopy “just in case”. The FC test changed that. Used well, it reduces unnecessary procedures while ensuring genuine inflammation isn’t missed.
How the test helps in practice
Faecal Calprotectin result (µg/g) | Meaning | Suggested next step |
|---|---|---|
Book a consultation right now! | ||
< 50 | IBD very unlikely | Manage as IBS if no alarm features |
50 – 200 | Borderline (“grey zone”) | Exclude infection/NSAIDs → repeat in 6–8 weeks |
> 200 | Likely inflammation | Refer for colonoscopy or imaging |
> 500 | Severe inflammation very likely | Prompt gastroenterology review |
Real-world examples from clinic
1. Avoiding colonoscopy in IBS
A 35-year-old with alternating bowel habits had an FC < 50 µg/g. With no red-flag symptoms, they were safely managed for IBS through diet and lifestyle. No endoscopy required.
Learning point: Low FC reliably excludes significant inflammation in low-risk patients.
2. Catching early IBD
A 22-year-old presented with mild pain and intermittent loose stools. FC > 600 µg/g; colonoscopy confirmed ulcerative colitis.
Learning point: High FC can reveal sub-clinical inflammation and speed up diagnosis.
3. False-positive elevation
A 70-year-old on long-term NSAIDs had FC ≈ 250 µg/g but a normal colonoscopy. After stopping NSAIDs, FC normalised.
Learning point: Always interpret FC in context: medications, infection, or even colorectal cancer can raise levels.
Putting results into context
False positives – recent infections, NSAID use, diverticulitis, or colorectal neoplasia may mimic inflammation.
False negatives – patchy disease (e.g. small-bowel Crohn’s or proctitis) can yield a normal FC.
Handling errors or sample dilution occasionally reduce readings.
At LSDC, we never act on an isolated number. We review the whole picture: symptoms, blood markers, age, medication, and risk factors, before deciding the next step.
Our stepwise approach
Assess the context: age, symptoms, red flags, medications.
Exclude confounders: infections, NSAIDs.
Interpret FC value (see table above).
Repeat if borderline.
Correlate with CRP, ESR, and haemoglobin.
Plan next step: reassurance, repeat testing, or colonoscopy.
Trends often matter more than single numbers. Rising FC suggests active inflammation; falling values imply improvement or resolution.
While NHS testing usually requires GP referral and lab analysis, LSDC Clinic offers private testing with faster turnaround and direct gastroenterology follow-up.
Explaining results to patients
We often describe FC as a “smoke detector for gut inflammation.”
If it’s quiet (low), there’s unlikely to be a fire.
If it’s loud (high), we look for what’s burning.
For borderline results, reassurance is paired with safety-netting:
“Your level is slightly raised, but not in the range we see with serious inflammation. We’ll repeat it in a few weeks to check it’s settling.”