TL;DR — Bottom Line
- Calprotectin is a neutrophil protein. Its level in stool reflects how many white cells are migrating into the gut, which makes it a direct marker of intestinal inflammation rather than a proxy.
- Its best-established use is distinguishing IBS from IBD. IBS is a disorder of gut-brain interaction without inflammation, so calprotectin is typically normal; active Crohn's or ulcerative colitis raises it.
- It is not specific to IBD. NSAIDs, infections, coeliac disease, diverticulitis, polyps and colorectal cancer all raise it. A high result means inflammation, not a diagnosis.
- The strongest everyday use is monitoring known IBD — tracking response to treatment and detecting relapse before symptoms return, without repeat endoscopy.
- Stop NSAIDs before testing. Ibuprofen and similar drugs raise calprotectin in a large proportion of users and are the most common avoidable cause of a misleading result.
Quick Picks
Calprotectin is a calcium-binding protein that makes up a substantial fraction of the cytosolic protein in neutrophils. When neutrophils migrate into the intestinal wall in response to inflammation, some are shed into the lumen and their calprotectin ends up in stool, where it is remarkably stable for days at room temperature.
That stability and that direct relationship to neutrophil traffic are what make it useful. It is one of the few genuinely good non-invasive markers in gastroenterology — not a wellness metric but a test used in clinical practice to decide who needs a colonoscopy and whether a treatment is working.
What Calprotectin Distinguishes
| Condition | Typical calprotectin | What it means |
|---|---|---|
| Irritable bowel syndrome | Normal | Symptoms without mucosal inflammation |
| Active Crohn's or ulcerative colitis | Raised, often markedly | Neutrophil infiltration of the gut wall |
| IBD in remission | Normal or near-normal | Useful for confirming and monitoring remission |
| NSAID enteropathy | Raised | Common false lead — stop NSAIDs before testing |
| Gastrointestinal infection | Raised | Transient; repeat after resolution |
| Colorectal cancer or polyps | May be raised | Non-specific — requires investigation |
| Coeliac disease | May be mildly raised | Consider alongside coeliac serology |
The IBS Versus IBD Question
Irritable bowel syndrome and inflammatory bowel disease can present similarly — abdominal pain, altered bowel habit, urgency, bloating — and they are fundamentally different conditions. IBS is a disorder of gut-brain interaction with no mucosal inflammation and no structural damage. IBD is immune-mediated inflammation that damages the bowel wall and, untreated, causes strictures, fistulas and an increased cancer risk.
Because IBS produces no neutrophil infiltration, calprotectin is typically normal in it. Because active IBD does, calprotectin is typically raised. That makes the test genuinely useful as a triage tool: in someone with chronic symptoms and no alarm features, a clearly normal calprotectin makes IBD unlikely and can spare an endoscopy, while a clearly raised one moves investigation forward quickly.
Where the Result Is Ambiguous
Calprotectin results fall into three practical zones rather than two. Clearly low results are reassuring for IBD. Clearly high results indicate inflammation that needs investigation. In between sits a borderline band where the sensible response is usually to repeat the test after a few weeks, having removed the obvious confounders.
Exact cut-offs vary between assays and laboratories, which is why comparing a number from one test against a threshold quoted for another is a mistake. If you are tracking calprotectin over time, use the same test and the same laboratory, and interpret the trend rather than the absolute value against a remembered number.
What Else Raises It
NSAIDs are the most common confounder and the most easily avoided. Ibuprofen, naproxen and related drugs cause small intestinal inflammation in a substantial proportion of regular users, and they raise calprotectin accordingly. Stopping them for a period before testing — typically at least a month, following your kit's guidance — removes the most frequent source of a misleading result.
Beyond that: any gastrointestinal infection, coeliac disease, diverticulitis, colorectal polyps and cancer can all raise calprotectin. Proton pump inhibitors have been associated with mild elevations. It rises with age in the absence of disease, and it is unreliable in infants, where normal levels are much higher. A raised calprotectin is a finding that requires explanation, not a diagnosis in itself.
Monitoring Known IBD Is Where It Earns Its Place
For someone with an established diagnosis of Crohn's disease or ulcerative colitis, calprotectin provides something valuable: an objective measure of mucosal inflammation without a colonoscopy. Symptoms correlate imperfectly with actual inflammation — people can feel well with active disease, and can have significant symptoms with a healed mucosa — so a marker that tracks the underlying process is genuinely informative.
It is used to confirm that a treatment is working, to support decisions about escalating or de-escalating therapy, and to detect a relapse early, since calprotectin frequently rises before symptoms return. Serial home testing between appointments, with results shared with the treating team, is an established use rather than a novelty.
Home Tests: Quantitative or Do Not Bother
Home calprotectin tests fall into two groups. Semi-quantitative strips give a coarse band — low, borderline, high — read by eye or by a phone camera. Quantitative tests report an actual number, either through a laboratory or through a calibrated reader.
For a single screening question — is there inflammation or not — a semi-quantitative test can be adequate. For anything involving tracking, it is not: you cannot follow a trend in a category. If you have IBD and want to monitor, buy a quantitative test and stay with the same one, because the numbers from different assays are not interchangeable.
Test Types Worth Considering
The main distinction is whether the result is a number or a band. If you intend to test more than once, that distinction decides the purchase.
Quantitative Laboratory Calprotectin Test
A stool sample stabilised and posted to a laboratory, returning an actual numeric result in micrograms per gram. The number is what makes serial testing meaningful and what a gastroenterologist can act on. Calprotectin is unusually stable in stool, so postal delay is less of a problem than with many stool tests. Stop NSAIDs beforehand per the kit's instructions.
Who it is for: anyone investigating chronic gut symptoms, and anyone with IBD who wants a result their clinician can use.
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Shop Fecal Calprotectin Lab Test Kits on AmazonHome Quantitative Test With Reader or App
Produces a numeric result at home, usually by photographing a developed cassette with a calibrated app. Designed for repeated use, which is exactly the use case where calprotectin is most valuable — tracking inflammation between clinic appointments and catching a relapse before symptoms return. Stay with one system, since values from different assays are not directly comparable.
Who it is for: people with diagnosed IBD monitoring disease activity between appointments.
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Shop Home Calprotectin Test Kits with App on AmazonSemi-Quantitative Calprotectin Strip Test
A cheaper strip giving a banded result rather than a number. Adequate for a one-off screening question in someone with chronic symptoms and no alarm features, where the question is simply whether inflammation is present. Inadequate for monitoring, because you cannot follow a trend in a category, and borderline results are common and hard to interpret.
Who it is for: one-off screening on a budget, where a clearly normal or clearly raised answer would be enough.
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Shop Calprotectin Rapid Test Strips on AmazonStool Collection Kit and Hygiene Supplies
Sample collection is the step people find off-putting and the step where results get compromised. A proper collection device that sits on the toilet rim, gloves, and wipes make the process considerably less unpleasant and reduce the chance of a contaminated or inadequate sample requiring a repeat. Cheap, and it is why some kits never get used after purchase.
Who it is for: anyone doing stool testing of any kind, particularly repeated testing.
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Shop Stool Sample Collection Kits on AmazonParacetamol as an NSAID Alternative
NSAIDs are the single most common avoidable cause of a raised calprotectin, because they cause small intestinal inflammation in a large proportion of regular users. If you take ibuprofen or naproxen regularly and need to test, you need an alternative for the washout period. Paracetamol does not have the same effect on the gut lining. Discuss any change with a clinician if the NSAID is treating a specific condition.
Who it is for: regular NSAID users preparing for a calprotectin test.
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Shop Paracetamol and Acetaminophen on AmazonWhich One Fits Your Situation
Calprotectin is one of the genuinely good non-invasive tests in gastroenterology, and it is good precisely because it measures one specific thing well: neutrophils in the gut. It does not tell you why they are there.
That makes it excellent at the question it is designed for — is this inflammation or is this IBS — and excellent at monitoring known disease, while never being a diagnosis on its own. A raised result is the beginning of an investigation, not the end of one.