Calprotectin levels in stool are a widely used marker of intestinal inflammation. If you’ve recently had a fecal calprotectin test or are considering one, you likely want to know what your result means, what a concerning level is, and what to do next. This guide explains calprotectin normal ranges by age, what high levels may indicate, and how this test fits with other gut-health assessments like microbiome testing.
What Is Calprotectin and Why Is It Measured in Stool?
Calprotectin is a protein released by neutrophils, a type of white blood cell, when there is inflammation in the intestinal lining. A stool calprotectin test measures this protein in a stool sample, providing a noninvasive way to detect gut inflammation. Clinicians use it to help differentiate between inflammatory bowel disease (IBD) and functional disorders like irritable bowel syndrome (IBS), and to monitor disease activity in people already diagnosed with IBD.
The test is sensitive but not specific—elevated levels indicate inflammation, but they do not tell you the cause. That’s why doctors look at calprotectin alongside symptoms, blood tests, imaging, and sometimes endoscopy. Understanding your result in context is key to making informed decisions about your health.
How the Fecal Calprotectin Test Works
You collect a small stool sample at home using a kit, then send it to a lab. The lab uses an immunoassay to measure calprotectin concentration, usually reported in micrograms per gram (µg/g). Results are typically available within a few days. The test is noninvasive and relatively low-cost, making it a practical first step for evaluating gut symptoms.
Calprotectin Normal Ranges by Age and Interpretation
There is no single universal “normal” calprotectin level—it varies by age and laboratory. However, common interpretation categories are:
- Normal (less than 50 µg/g): Generally indicates little or no intestinal inflammation.
- Borderline (50–150 µg/g): May indicate mild inflammation, early disease, or assay variability; repeat testing is often recommended.
- Elevated (above 150 µg/g, especially above 250–300 µg/g): Suggests active intestinal inflammation and usually prompts further evaluation.
Infants and older adults may naturally have higher baseline levels, so age-specific ranges are used in some settings. Always compare your result to the reference range provided by your lab and discuss it with your clinician.
What Level of Calprotectin Is Concerning?
A calprotectin level above 150 µg/g is generally considered elevated and may warrant further investigation. Levels above 250–300 µg/g are more strongly associated with active inflammation and often lead to referral for colonoscopy or imaging. However, the level alone is not a diagnosis—your symptoms and other test results matter just as much. A concerning level is one that is persistently high or accompanied by red-flag symptoms like significant rectal bleeding, rapid weight loss, or severe abdominal pain.
When to Worry About Calprotectin Levels
You should be concerned if your calprotectin is high and you experience any of the following: high fever, severe abdominal pain, visible blood in stool, unexplained weight loss, or persistent vomiting. These symptoms can indicate a serious condition requiring prompt medical evaluation. Even without these symptoms, a very high result (e.g., >500 µg/g) should be reviewed by a healthcare provider.
Main Causes of High Calprotectin: Beyond IBD
While calprotectin is closely associated with inflammatory bowel disease (Crohn’s disease and ulcerative colitis), many other conditions and factors can raise levels. Understanding these helps you avoid jumping to conclusions.
- Infections: Bacterial gastroenteritis, diverticulitis, or other intestinal infections.
- Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can temporarily elevate calprotectin.
- Recent procedures: Colonoscopy or bowel surgery can cause transient inflammation.
- Other conditions: Celiac disease, colorectal cancer, and microscopic colitis can also increase calprotectin.
This is why a single high result does not mean you have IBD. Your doctor will review your full clinical picture before making a diagnosis.
Can You Have High Calprotectin Without IBD?
Yes. As mentioned above, infections, NSAID use, and other conditions can all elevate calprotectin. In fact, a significant percentage of people with high calprotectin do not end up having IBD after further testing. That’s why your clinician will likely recommend additional tests to confirm or rule out IBD before any long-term treatment.
Is Calprotectin a Tumor Marker?
Calprotectin is not a tumor marker. It is an inflammatory marker, and while colorectal cancer can cause inflammation that raises calprotectin, the test is not designed to detect cancer. There are other markers and screening methods, like colonoscopy, that are used to screen for colorectal cancer. If you have symptoms like unexplained bleeding or weight loss, talk to your doctor about appropriate cancer screening.
What Level of Calprotectin Warrants a Colonoscopy?
There is no absolute threshold that automatically requires a colonoscopy, but levels consistently above 150–250 µg/g, especially with symptoms like diarrhea, bleeding, or weight loss, often prompt evaluation with colonoscopy. Doctors also consider your age, family history, and other risk factors. A colonoscopy allows direct visualization of the intestinal lining and biopsy to determine the cause of inflammation.
Calprotectin in Blood vs Stool: What’s the Difference?
Most calprotectin testing is done on stool, but there is also a blood test for calprotectin. The stool test is more specific for intestinal inflammation, while blood calprotectin reflects systemic inflammation and is less commonly used for gut health. Stool calprotectin is the standard for assessing IBD activity and distinguishing it from IBS. Blood calprotectin may be used in research or for systemic inflammatory conditions but has limited role in routine gut evaluation.
When Your Calprotectin Is High: What to Do Next
If your calprotectin comes back high, don’t panic. Here’s a practical step-by-step plan:
- Review your result with your doctor. Discuss any medications, recent infections, or procedures that might have affected it.
- Ask about repeat testing. A single elevated value is often confirmed with a second test before major investigations.
- Expect further evaluation. Your doctor may recommend stool pathogen tests, blood tests, imaging, or colonoscopy depending on your symptoms.
- Consider microbiome testing. Combining calprotectin with a gut microbiome analysis can provide clues about underlying microbial imbalances linked to inflammation. InnerBuddies offers a detailed gut microbiome test that can complement your calprotectin results.
Can You Have IBD if Calprotectin Is Normal?
Yes, it is possible, though less common. Calprotectin is sensitive for neutrophil-driven inflammation, but some cases of IBD, especially in early stages or limited to the small intestine, may have normal or borderline levels. Conversely, a normal calprotectin makes IBD less likely but does not rule it out entirely. If symptoms persist despite a normal result, your doctor may still consider further evaluation.
Lifestyle and Dietary Considerations for High Calprotectin
While calprotectin is not directly managed by diet, certain foods and habits can influence intestinal inflammation. If your calprotectin is elevated, consider these general approaches to support gut health:
- Eat a fiber-rich diet with a variety of fruits, vegetables, and whole grains to support beneficial gut bacteria.
- Limit processed foods and excessive alcohol, which can negatively affect the microbiome.
- Stay hydrated and manage stress, as stress can impact gut function.
- Avoid NSAIDs if possible, as they can irritate the gut lining and raise calprotectin.
Note that these are general tips—they are not a substitute for medical advice. Always discuss dietary changes with a healthcare provider, especially if you have an underlying condition.
How Microbiome Testing Complements Calprotectin
The gut microbiome—the community of microorganisms in your intestines—interacts closely with the immune system. Dysbiosis, or imbalance in the microbiome, can contribute to inflammation and higher calprotectin levels. Microbiome testing measures bacterial diversity, composition, and functional pathways, such as the production of short-chain fatty acids (SCFAs) like butyrate, which support gut lining health.
Pairing calprotectin with microbiome testing can help you understand not just whether inflammation is present, but why it might be occurring. For example, reduced SCFA-producing bacteria alongside elevated calprotectin may suggest a microbial contribution to inflammation that could be addressed with dietary strategies. InnerBuddies offers a comprehensive gut microbiome test and subscription options for longitudinal monitoring.
Frequently Asked Questions About Calprotectin
What is a concerning level of calprotectin?
Levels above 150 µg/g are generally considered elevated and worth investigating, especially if symptoms are present. Levels above 250–300 µg/g are more concerning and usually prompt further testing like colonoscopy.
What is the normal range of calprotectin by age?
Normal ranges can vary by age. In infants, normal levels may reach 200 µg/g, while in adults, normal is usually below 50 µg/g. Older adults may have slightly higher baselines. Always compare with your lab’s reference range.
What is the main cause of high calprotectin?
The most common cause is inflammatory bowel disease (IBD), but infections, NSAID use, and other inflammatory conditions can also elevate levels. The cause is determined through further diagnostic testing.
What cancers cause high calprotectin levels?
Colorectal cancer can cause elevated calprotectin due to the associated inflammation, but calprotectin is not a cancer marker. Other gastrointestinal cancers may also produce inflammation, but this test is not used for cancer screening.
Is a stool calprotectin level of 30 considered high?
No, 30 µg/g is within the normal range (below 50 µg/g). It indicates no significant intestinal inflammation.
How do you live with IBD?
Living with IBD often involves medication, dietary adjustments, stress management, and regular monitoring. Work closely with a gastroenterologist to develop a personalized treatment plan. Calprotectin testing can track disease activity over time.
What foods should I eat and avoid if I have IBD?
During flare-ups, low-fiber foods may be easier on the gut. Between flares, a balanced diet with fruits, vegetables, and lean proteins is generally recommended. Avoid trigger foods like spicy items or high-fat meals if they worsen symptoms. Always consult a dietitian for personalized advice.
Key Takeaways
- Calprotectin is a marker of intestinal inflammation, not a specific disease test.
- Normal is usually below 50 µg/g; elevated is above 150 µg/g; levels above 250–300 µg/g are more concerning.
- High calprotectin can be caused by IBD, infections, NSAIDs, and other conditions—context is key.
- Calprotectin is not a tumor marker and cannot diagnose cancer.
- Microbiome testing can add valuable context when calprotectin is persistently high or symptoms are unexplained.
Always discuss your calprotectin results with a healthcare provider to determine the best next steps for your specific situation.
