Fecal Calprotectin: Normal Range + What High Levels Can Mean for UC
Last Updated Jan 15, 2026
Fecal calprotectin is a “stool test inflammation” marker that often shows up during ulcerative colitis (UC) diagnosis or when symptoms change. Seeing a number on a lab report can feel confusing, especially when the result is labeled borderline or high. This quick guide explains the fecal calprotectin normal range in ulcerative colitis, why different labs use different cutoffs, and what higher results can suggest, without trying to replace medical care.
What fecal calprotectin measures (and why it matters in UC diagnosis)
Calprotectin is a protein released during inflammation, and fecal calprotectin testing measures how much of it is present in a stool sample. For UC, the key idea is that this test reflects inflammation in the lining of the intestines, which can be present even when symptoms feel mild, or sometimes when symptoms and inflammation do not match perfectly. Because colonoscopy is the main way to directly see and confirm inflammation in UC, stool markers like fecal calprotectin are often used as a noninvasive way to help estimate what might be happening between procedures and to support decisions about whether more testing is needed. [1]
In UC monitoring, professional guidelines support using symptoms plus biomarkers together, instead of symptoms alone. For example, the American Gastroenterological Association (AGA) guideline discusses fecal calprotectin thresholds, noting that values under 150 micrograms per gram (µg/g) can help rule out active inflammation in people with UC who are in symptomatic remission, while values above 150 µg/g can suggest active inflammation in people with moderate to severe symptoms, with endoscopy still important when symptoms and biomarkers do not align. [2]
It also helps to know what the test cannot do. A raised result supports the presence of inflammation, but it does not prove UC is the cause. Patient education resources note that hospitals may use different cutoffs, and that infections (like gastroenteritis) can raise calprotectin too. Calprotectin can also be used over time to help check response to treatment, especially when tracked as a trend rather than a single number. [3]
Calprotectin levels chart: normal, borderline, high, and what happens next
Because reference ranges vary, the most important “calprotectin levels chart” is the one printed next to the result on the lab report. One commonly used set of cutoffs is:
Normal: <50 µg/g
Borderline calprotectin: 50 to 120 µg/g
High (abnormal): >120 µg/g
In this framework, borderline results may reflect mild inflammation (including treated inflammatory bowel disease) and may also be seen with certain medicines such as nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin. Many clinicians consider a calprotectin repeat test in about 4 to 6 weeks when results are borderline and symptoms suggest ongoing concern. [4]
Other health systems use different “action ranges,” especially in primary care, such as: <100 µg/g (normal), 100 to 250 µg/g (equivocal), >250 µg/g (more consistent with active inflammation). In that model, an equivocal result may lead to repeat testing in 2 to 4 weeks, and persistent elevation may prompt discussion about gastroenterology evaluation. [5]
When calprotectin is high in UC, it can line up with active intestinal inflammation, but there are several reasons a number may be unexpectedly elevated or difficult to interpret. Lab guidance notes that fecal calprotectin is not diagnostic on its own, and normal results do not fully exclude inflammatory bowel disease. Borderline results may also be seen with proton-pump inhibitors, and elevations can occur with other inflammatory conditions (including infections, celiac disease, or colorectal cancer). Results can also vary because calprotectin is not evenly distributed throughout a stool sample, so repeat testing is sometimes used to confirm a pattern. [6]