High Fecal Calprotectin: Causes, Interpretation & When to Seek Help

Discovering a high fecal calprotectin level can be confusing. This guide clearly explains what the test is, what a high result typically means, and the most common causes—from bacterial infections to inflammatory bowel disease. You’ll learn how to interpret levels, key considerations like when to worry, and logical next steps to discuss with your healthcare professional.

What Is a Fecal Calprotectin Test?

A fecal calprotectin test measures the amount of a specific protein, calprotectin, in your stool. This protein is released by neutrophils, which are white blood cells that rush to the gut lining during inflammation. The test’s primary purpose is to help distinguish inflammatory gut conditions (like infectious colitis or inflammatory bowel disease) from non-inflammatory functional disorders like irritable bowel syndrome (IBS). It is a non-invasive, useful screening tool that your doctor may recommend if you have persistent digestive symptoms.

Doctors often order this test for individuals experiencing:

• Chronic or recurrent diarrhea, especially with blood or mucus
• Unexplained abdominal pain or cramping
• A need to differentiate between IBS and an inflammatory condition
• Monitoring of known inflammatory bowel disease (IBD) activity

What Does a High Fecal Calprotectin Level Mean?

A high fecal calprotectin level directly signals that there is active, neutrophil-driven inflammation in your intestinal lining. The key point is that the test indicates inflammation but does not identify its specific cause.

Interpretation depends on the magnitude:

• Normal/Low: Typically <50 µg/g suggests significant mucosal inflammation is unlikely.
• Borderline/Elevated: 50–120 µg/g may be seen in mild inflammation, some infections, or with medications like NSAIDs.
• High/Strongly Elevated: >120 µg/g often points to more significant inflammatory activity, as commonly seen in active infectious colitis or flare-ups of IBD (Crohn’s disease, ulcerative colitis).

Note: Reference ranges can vary between laboratories. Always discuss your specific result with your clinician.

Common Causes of High Fecal Calprotectin

1. Bacterial Infections (Infectious Colitis)

Acute bacterial infections are a frequent cause of high calprotectin. Invasive or toxin-producing pathogens trigger a strong neutrophil response, leading to marked inflammation. Common culprits include:

• Campylobacter jejuni/coli: Often from undercooked poultry.
• Salmonella enterica: Linked to contaminated eggs, poultry, or produce.
• Shigella spp.: Causes dysentery with intense inflammation.
• Clostridioides difficile (C. diff): Often follows antibiotic use.
• E. coli strains (EIEC, STEC): Can be invasive or toxin-producing.
• Yersinia enterocolitica: Associated with undercooked pork.

Identifying a bacterial cause requires specific diagnostic tests like stool culture or PCR panels, as calprotectin itself cannot pinpoint the organism.

2. Inflammatory Bowel Disease (IBD)

Persistently high or recurrently elevated calprotectin is a hallmark of active Crohn’s disease or ulcerative colitis. The test is widely used to monitor disease activity and response to treatment. Levels can fluctuate with flare-ups.

3. Other Inflammatory Gut Conditions

• Diverticulitis: Inflammation of small pouches (diverticula) in the colon can elevate calprotectin.
• Microscopic Colitis: Causes chronic watery diarrhea and inflammation visible only under a microscope.
• NSAID-Induced Enteropathy: Regular use of non-steroidal anti-inflammatory drugs (e.g., ibuprofen, naproxen) can injure the gut lining and raise levels.

4. Non-Bacterial Infections

High calprotectin is not exclusive to bacteria. Viral infections (norovirus, rotavirus) and parasitic infections (Giardia, Entamoeba histolytica) can also cause inflammatory diarrhea and elevated results.

5. Other Factors & Confounders

• Certain Medications: Primarily NSAIDs, but others can occasionally affect the gut.
• Intense Endurance Exercise: Can transiently increase intestinal permeability and calprotectin.
• Gastrointestinal Bleeding or Recent Procedures: May cause temporarily elevated levels.

When Should You Worry About High Calprotectin?

This is a crucial question. The urgency and need for further action depend on the context of your symptoms and medical history.

Consult a healthcare professional promptly if you have:

• A very high calprotectin result (e.g., significantly above 200-250 µg/g).
• Results that are persistently elevated over time, especially if symptoms continue.
• Significant symptoms like blood in stool, persistent fever, unintentional weight loss, or severe pain.
• A personal or family history of inflammatory bowel disease or colorectal cancer.

A single, mildly elevated result without concerning symptoms may be less urgent but still warrants discussion with your doctor to determine if monitoring or basic additional testing is needed.

How to Treat High Calprotectin: Next Steps & Testing

The treatment addresses the underlying cause, not the calprotectin level itself. The appropriate next steps are determined by your clinician based on your full picture.

A typical diagnostic pathway may include:

1. Clinical Evaluation: Review of symptoms, medical history, medications, and risk factors.
2. Targeted Stool Testing: If an infection is suspected, your doctor may order a stool PCR panel or culture to identify specific pathogens like bacteria or parasites.
3. Imaging or Endoscopy: For persistent or unexplained inflammation, a colonoscopy may be recommended to visually assess the colon and obtain biopsies, especially to rule out or confirm IBD, microscopic colitis, or other structural issues.
4. Microbiome Analysis for Context: Tools like the InnerBuddies Microbiome Test do not diagnose acute infections but can provide valuable educational insights into your gut ecosystem’s balance. This can reveal patterns of dysbiosis that may contribute to ongoing inflammation, offering context for personalized diet and lifestyle discussions with your care team.

The Role of Gut Microbiome and Dysbiosis

Even after an acute infection resolves, an imbalanced gut microbiome (dysbiosis) can sometimes perpetuate low-grade inflammation that keeps calprotectin elevated. For instance, an overgrowth of opportunistic bacteria like Enterobacteriaceae or a loss of beneficial, anti-inflammatory microbes can create a pro-inflammatory environment.

While not a first-line diagnostic tool, a comprehensive microbiome analysis can be a helpful next step for those with recurrent symptoms or persistently borderline results. It provides a snapshot of your microbial community, highlighting diversity, the presence of potential pathobionts, and functional capacity, which can inform a more holistic approach to supporting gut health.

Key Takeaways

• Fecal calprotectin is a reliable biomarker for intestinal inflammation but is not specific to any single cause.
• High levels can be caused by bacterial infections, IBD, diverticulitis, NSAIDs, and other inflammatory conditions.
• Interpretation requires clinical context—symptoms, history, and sometimes repeat testing.
• Seek medical advice for persistently high results, especially with red-flag symptoms like rectal bleeding or weight loss.
• Targeted stool tests are needed to identify specific pathogens; microbiome testing can offer additional context for long-term gut health.

Frequently Asked Questions

What does it mean if your faecal calprotectin is high?

A high fecal calprotectin result means there is active inflammation in your intestinal lining. This inflammation could stem from various sources, including an infection (bacterial, viral, or parasitic), inflammatory bowel disease (IBD), diverticulitis, medication side effects, or other inflammatory conditions. The test signals that further investigation is often needed to pinpoint the exact cause.

How to treat high calprotectin in stool?

You treat the underlying condition causing the high calprotectin, not the number itself. Treatment depends entirely on the diagnosis. For a bacterial infection, targeted antibiotics may be used. For IBD, anti-inflammatory medications are standard. For NSAID-induced enteropathy, discontinuing or changing the medication under a doctor's guidance is key. Always follow your healthcare professional's treatment plan.

Can high calprotectin mean diverticulitis?

Yes, acute diverticulitis—an inflammation or infection of small pouches in the colon—is a known cause of elevated fecal calprotectin. If you have symptoms like left-sided abdominal pain, fever, and a high calprotectin level, your doctor may consider diverticulitis as a possible diagnosis and may use imaging (like a CT scan) to confirm it.

When to worry about calprotectin?

Worry warrants action. You should take a high calprotectin result seriously and consult a doctor, especially if it is accompanied by concerning symptoms: persistent diarrhea, blood in your stool, fever, unintended weight loss, or severe abdominal pain. Persistently high levels without an obvious, easily treatable cause (like a simple infection) also require further medical evaluation.

Keywords

high fecal calprotectin, what is fecal calprotectin test, causes of high calprotectin, calprotectin elevation causes, bacteria causing high calprotectin, inflammatory bowel disease IBD, infectious colitis, diverticulitis calprotectin, when to worry about calprotectin, gut microbiota imbalance, stool inflammation biomarker, interpreting calprotectin results