Calprotectin Explained: Levels, Causes & What They Mean


Author: InnerBuddies

Updated: August 11, 2026


Calprotectin Explained: What It Is and Why It Matters

Calprotectin is a protein released by neutrophils during inflammation in the gastrointestinal tract. Measured through a simple, noninvasive stool test, it serves as a key biomarker for gut inflammation. Normal levels are typically below 50 µg/g, while levels above 100 µg/g may indicate significant inflammation that warrants further investigation. This test helps healthcare providers distinguish between inflammatory bowel disease (IBD) and functional conditions like irritable bowel syndrome (IBS), guiding more accurate diagnoses and reducing the need for unnecessary invasive procedures.

Interpreting Calprotectin Levels: Normal, Concerning, and High

Understanding calprotectin levels is essential for interpreting your gut health. Levels below 50 µg/g are generally considered normal and can help rule out significant inflammation. Levels between 50 and 100 µg/g are borderline and may require repeat testing or correlation with symptoms. Levels above 100 µg/g are concerning and often prompt further evaluation, such as colonoscopy, to identify the underlying cause. However, calprotectin is not a tumor marker—it does not diagnose cancer. Instead, it indicates the presence of inflammation, which can result from infections, IBD, or other conditions.

Causes of High Calprotectin and Next Steps for Gut Health

High calprotectin levels are most commonly caused by inflammatory bowel diseases like Crohn’s disease and ulcerative colitis, but they can also result from infections, medication use, or strenuous exercise. The gut microbiome plays a significant role in modulating inflammation, and an imbalance (dysbiosis) may contribute to elevated levels. If your calprotectin is high, your doctor may recommend a colonoscopy to visualize the intestinal lining and obtain biopsies. For those with persistent symptoms, a gut microbiome test can provide additional insights, helping to personalize dietary and lifestyle strategies for better gut health.

2-minute self-check Is a gut microbiome test useful for you? Answer a few quick questions and find out if a microbiome test is actually useful for you. ✔ Takes 2 minutes ✔ Based on your symptoms & lifestyle ✔ Clear yes/no recommendation Check if a test is right for me

Discover the Microbiome Test

ISO-certified EU lab • Sample stays stable during shipping • GDPR-secure data

Microbiome Test Kit

Calprotectin is a protein released by white blood cells, mainly neutrophils, in response to inflammation in the gastrointestinal tract. A fecal calprotectin test measures this protein in stool, providing a noninvasive way to detect gut inflammation. It helps doctors distinguish between inflammatory bowel disease (IBD) and functional conditions like irritable bowel syndrome (IBS). This article explains what calprotectin is, what your levels mean, and answers common questions like "What level of calprotectin is concerning?" and "Is calprotectin a tumor marker?"

What Is Calprotectin and How Does the Test Work?

The Biological Role of Calprotectin

Calprotectin is a calcium-binding protein that helps regulate inflammation. It is released by neutrophils during inflammatory responses, particularly in the gut. When there is inflammation in the intestinal lining, calprotectin levels in stool rise, making it a reliable marker for mucosal inflammation.

How Fecal Calprotectin Testing Works

The test requires a small stool sample, which you can collect at home and send to a lab. The lab measures the concentration of calprotectin in the sample. Results are typically available within a few days. This noninvasive approach helps avoid unnecessary invasive procedures like colonoscopy when inflammation is not present.

Interpreting Calprotectin Levels: Normal, Concerning, and High

Understanding your calprotectin levels is crucial for determining next steps. Here’s a quick guide:

  • Normal: Below 50 µg/g – likely no significant inflammation.
  • Borderline: 50–100 µg/g – may need repeat testing or correlation with symptoms.
  • Concerning: Above 100 µg/g – indicates significant inflammation, often prompting further investigation.

What Level of Calprotectin Is Concerning?

Levels above 100 µg/g are generally considered concerning and may warrant a colonoscopy to visualize the intestinal lining and identify the cause of inflammation. However, your doctor will interpret this in the context of your symptoms and medical history. Borderline levels (50–100 µg/g) may require repeat testing or additional assessments.

What Level Warrants a Colonoscopy?

A colonoscopy is often recommended when calprotectin levels are significantly elevated (usually above 100 µg/g) and symptoms persist. This procedure allows doctors to directly inspect the colon and take tissue samples if needed. High calprotectin alone does not confirm a diagnosis; it simply indicates that further investigation is necessary.

What Causes High Calprotectin Levels?

High calprotectin levels are most commonly associated with inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis. However, other factors can also elevate levels:

  • Infections (bacterial, viral, or parasitic)
  • Use of nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen
  • Recent strenuous exercise
  • Advanced age

These factors can cause false positives, so your doctor will consider your overall health and symptoms when interpreting results.

Is Calprotectin a Tumor Marker?

No, calprotectin is not a tumor marker. It is an inflammation marker. While inflammation can be associated with certain cancers, calprotectin alone cannot diagnose cancer. If cancer is suspected, your doctor will recommend specific cancer screening tests, such as imaging or colonoscopy with biopsy.

Calprotectin vs. CRP: Understanding the Difference

C-reactive protein (CRP) is a blood marker for systemic inflammation, while calprotectin specifically reflects inflammation in the gastrointestinal tract. Both can be elevated in IBD, but calprotectin offers better accuracy for intestinal inflammation and can help differentiate IBD from IBS. Your doctor may use both markers to get a fuller picture of your health.

The Role of the Gut Microbiome in Calprotectin Levels

The gut microbiome—the trillions of microorganisms in your intestines—plays a key role in regulating inflammation. An imbalance, known as dysbiosis, can trigger or worsen inflammation, potentially leading to elevated calprotectin levels. Factors like diet, antibiotics, and infections can disrupt microbial balance, influencing both gut health and calprotectin.

How Microbiome Testing Complements Calprotectin Results

A gut microbiome test can reveal the diversity and composition of your gut bacteria, offering insights into potential inflammation drivers. For those with persistent GI symptoms or elevated calprotectin, combining microbiome data with calprotectin results can help create a more personalized management plan. However, microbiome testing does not replace medical evaluation—it complements it.

Symptoms That May Prompt Calprotectin Testing

Your doctor may recommend a fecal calprotectin test if you experience:

  • Chronic diarrhea or loose stools
  • Persistent abdominal pain or cramping
  • Blood or mucus in the stool
  • Unexplained weight loss

These symptoms can indicate inflammation, but they also occur in functional disorders like IBS. Calprotectin helps differentiate between the two.

Limitations and Factors That Affect Calprotectin Levels

Calprotectin levels can be influenced by factors unrelated to gut inflammation. Infections, NSAIDs, strenuous exercise, and age can affect results. Additionally, laboratory reference ranges may vary, so it’s important to interpret results with your healthcare provider. A single borderline result may not be conclusive; your doctor might recommend repeat testing or trend monitoring.

When to Consider Further Testing: Colonoscopy and Beyond

If your calprotectin level is high (above 100 µg/g) and you have symptoms, your doctor may recommend a colonoscopy to examine the intestinal lining and take biopsies. This helps diagnose IBD, infections, or other conditions. A normal calprotectin level can help avoid unnecessary procedures, but if symptoms persist, further evaluation may still be needed.

Key Takeaways: Calprotectin and Your Gut Health

  • Calprotectin is a noninvasive marker of gut inflammation, not a tumor marker.
  • Normal levels below 50 µg/g; concerning levels above 100 µg/g.
  • High levels may indicate IBD, infection, or other inflammation causes.
  • Microbiome testing can provide additional insights into inflammation drivers.
  • Always discuss your results with a healthcare provider to determine next steps.

Frequently Asked Questions

What level of calprotectin is concerning?

Levels above 100 µg/g are generally considered concerning and warrant further investigation. Borderline levels (50–100 µg/g) may need repeat testing or correlation with symptoms.

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.

Is calprotectin a tumor marker?

No, calprotectin is an inflammation marker, not a tumor marker. It does not diagnose cancer.

What level of calprotectin warrants a colonoscopy?

Levels above 100 µg/g, especially with persistent symptoms, often lead to a colonoscopy recommendation to identify the cause of inflammation.