Calprotectin vs CRP for Crohn’s: Which Tracks Gut Inflammation Better?
Last Updated Jan 15, 2026
Living with Crohn’s disease often means tracking symptoms and also tracking inflammation, because the two do not always line up. Two common lab markers used for this are fecal calprotectin (a stool test) and C-reactive protein or CRP (a blood test). They measure different signals, rise for different reasons, and are often most helpful when viewed together over time.
What each test measures (and what it can miss)
Fecal calprotectin measures a protein released by certain white blood cells (neutrophils). When the gut lining is inflamed, more of this protein can end up in stool. Because it comes from inflammatory activity in the intestines, calprotectin is generally considered more “gut-focused” than blood markers, and it can help show whether symptoms are more likely tied to intestinal inflammation versus a functional condition such as irritable bowel syndrome (IBS). CRP, on the other hand, is made by the liver as part of the body’s general (whole-body) inflammatory response. It can rise quickly and fall quickly, which can make it useful for following changes, but it does not point to a specific location in the body. In Crohn’s disease, CRP is elevated in only a subset of people, and mild inflammation can still be present even when CRP is normal, which limits CRP as a stand-alone gut inflammation tracker. A related blood test, erythrocyte sedimentation rate (ESR) (sometimes called “sed rate”), is another non-specific inflammation marker, and it tends to be less direct for Crohn’s monitoring than calprotectin. [1]
Calprotectin vs CRP for Crohn’s: which tracks gut inflammation better, and how they’re used together
When the goal is to track inflammation inside the intestines, fecal calprotectin often has an advantage because it reflects inflammatory cells active in the gut. Many clinical teams use calprotectin to help decide when inflammation is unlikely, and when it may be worth confirming disease activity with imaging or endoscopy. The American Gastroenterological Association (AGA) suggests that, in people with Crohn’s disease who are in symptomatic remission and have had recent confirmation of endoscopic remission, a fecal calprotectin under 150 μg/g and/or CRP under 5 mg/L (or below a lab’s normal cutoff) can help rule out active inflammation and avoid routine endoscopic reassessment. [2]
CRP still adds value, especially when Crohn’s inflammation is more severe or when there is more systemic inflammation, but it is less reliable as a lone signal of intestinal healing. European Crohn’s and Colitis Organisation (ECCO) guidance notes that CRP can be specific at certain cutoffs for detecting endoscopic activity, but sensitivity can be poor, and a negative CRP does not exclude a flare. ECCO also notes that repeated fecal calprotectin measurements can outperform repeated CRP in some Crohn’s monitoring situations, such as early post-operative recurrence or small bowel follow-up. [3]
In real-world care, the most useful approach is often trend-based: comparing each person’s calprotectin and CRP patterns against past endoscopy or imaging results, rather than relying on a single number. This fits with treat-to-target thinking in inflammatory bowel disease, where symptom improvement and normalization of blood and stool markers are considered important short-term targets on the way toward deeper healing goals. [4]