Short answer
Fecal calprotectin and fecal lactoferrin are stool markers linked to neutrophil-driven intestinal inflammation. They help answer a limited but useful question: do symptoms look more inflammatory, as in possible IBD, or more functional, as in many IBS patterns? They do not identify the exact disease or the exact spot in the bowel.
How they compare
| Test | What it reflects | Important caveat |
|---|---|---|
| Fecal calprotectin | A neutrophil protein measured quantitatively in stool. | High results can occur with IBD, infection, NSAIDs, cancer, celiac disease, or other inflammation. |
| Fecal lactoferrin | Another neutrophil-associated stool protein. | Often used for the same inflammation question, but cutoffs and availability vary by lab. |
| Normal result | Can make active intestinal inflammation less likely. | False negatives can occur; symptoms and red flags still matter. |
| High result | Supports intestinal inflammation. | May require repeat testing, stool infection testing, imaging, or colonoscopy depending on the case. |
When to use each test
Calprotectin is the better-known and more widely used marker in many U.S. settings, but lactoferrin is also a useful stool inflammation marker. AGA guidance for ulcerative colitis uses either fecal calprotectin or fecal lactoferrin, along with symptoms, to help decide whether active inflammation is likely and whether endoscopy can be deferred. ACG guidance for Crohn's disease also gives both tests an adjunctive role.
What can distort the result
- Infection can raise either marker.
- NSAID use can push calprotectin upward.
- Borderline values can move with sampling variation or a changing flare.
- Neither test tells you whether the cause is Crohn's disease, ulcerative colitis, microscopic colitis, celiac disease, diverticulitis, or something else.
- NIDDK: Diarrhea
- NIDDK: Ulcerative Colitis Symptoms and Causes
Questions to ask
- Is the result low, borderline, or clearly elevated?
- Was there recent infection, NSAID use, or another known inflammatory condition?
- Would fecal calprotectin, lactoferrin, stool pathogen testing, or colonoscopy be the best next step?
- Do blood in stool, weight loss, fever, nighttime diarrhea, anemia, or family history make the situation more urgent?
Related guides: fecal calprotectin test, stool WBC test and inflammatory diarrhea, post-infectious IBS testing questions, and stool test vs microbiome test.
When one marker is not enough
Calprotectin and lactoferrin both reflect inflammation, but neither one by itself proves the diagnosis or the cause. If the marker is abnormal, the next step is usually to match the result with symptoms, medication use, and the right clinical workup.
FAQ
Which is better, calprotectin or lactoferrin?
Neither one is universally better. They both point toward intestinal inflammation, and the right choice often depends on the lab, local practice, and what the clinician is trying to answer.
Can these tests tell IBD from IBS?
They can help separate inflammatory from non-inflammatory patterns, but they do not diagnose IBD or IBS on their own.
Why is calprotectin used more often?
Calprotectin has broader availability and more published guidance in many settings, so clinicians often reach for it first.
Can infection or NSAIDs change the result?
Yes. Infection, NSAID use, and other inflammatory gut conditions can raise stool inflammatory markers.
When should the result trigger faster GI follow-up?
Very high or rising results, blood in stool, weight loss, fever, nighttime diarrhea, anemia, or strong family history should prompt faster follow-up.
Does a normal result rule out bowel disease?
No. It lowers the chance of active intestinal inflammation, but it does not rule out every digestive disease or every reason for symptoms.