High Calprotectin: What It Means, Causes, and Next Steps

Fecal calprotectin is a protein measured in stool that serves as a non-invasive marker for inflammation in the intestines. A high result indicates that your immune system is active in the gut, often due to conditions like inflammatory bowel disease (IBD) or an infection. This article provides a clear, practical guide to understanding what a high calprotectin level means, exploring potential causes, and outlining the typical next steps you and your doctor might consider.

In Plain Language: What Is Calprotectin and What Does a High Level Mean?

Calprotectin is a protein released by white blood cells called neutrophils when there is inflammation in the body. When measured in a stool sample (fecal calprotectin), it specifically indicates inflammation in the gastrointestinal tract. In simple terms, a high level means that there is likely active inflammation in your gut. This helps doctors distinguish between inflammatory conditions, like Crohn's disease or ulcerative colitis, and non-inflammatory conditions like irritable bowel syndrome (IBS), where inflammation is not typically present.

What does it mean if calprotectin is high?

If your fecal calprotectin test result is high, it primarily means that there is neutrophil-mediated inflammation occurring in your intestines. Neutrophils are a type of white blood cell that rush to areas of inflammation or infection. Their activity releases calprotectin, which can then be measured in the stool.

This elevation is a signal that something is activating your immune system within the gut. It is not a diagnosis in itself but rather a clue that guides further investigation. The degree of elevation can sometimes correlate with the severity of inflammation.

• Common causes of high calprotectin: Inflammatory Bowel Disease (IBD: Crohn's disease, ulcerative colitis), infectious colitis (bacterial, viral, or parasitic), diverticulitis.
• Less common causes: Microscopic colitis, NSAID-induced enteropathy, pouchitis (after bowel surgery), and in some cases, colorectal cancer.
• What doctors typically do next: A high result often leads to further tests, which may include a stool test for infections, blood tests, imaging like a CT scan, or a referral to a gastroenterologist for a colonoscopy to visualize the colon and take biopsies.

What cancers cause high calprotectin?

Colorectal cancer (cancer of the colon or rectum) can sometimes cause elevated fecal calprotectin levels. This is because the tumor can cause local inflammation and ulceration, which attracts neutrophils. However, it is crucial to understand that fecal calprotectin is not a reliable screening test for cancer. Its primary use is to detect inflammation, and there are many more common causes of inflammation than cancer.

If cancer is suspected based on other factors like symptoms, age, or family history, a doctor will recommend appropriate cancer screening methods, such as a colonoscopy, which is the gold standard.

Can food cause high calprotectin?

Food alone is unlikely to cause a sudden, significant spike in calprotectin levels that would typically be seen with conditions like IBD or an infection. However, your long-term dietary patterns can influence your overall gut environment and immune system.

A diet consistently low in fiber and high in processed foods may contribute to a state of low-grade inflammation and an imbalance in the gut microbiome (dysbiosis) over time. This environment could potentially influence calprotectin levels, but the effect is generally subtle compared to the sharp increase caused by an active inflammatory disease. Sudden, high elevations are more likely linked to a medical condition than to a specific food you ate.

How to treat high calprotectin in stool?

You do not treat the high calprotectin level itself; you treat the underlying condition causing the inflammation. The treatment approach depends entirely on the diagnosis.

• If the cause is IBD: Treatment focuses on reducing inflammation with medications such as anti-inflammatories, immunosuppressants, or biologics. Diet and lifestyle changes may also be recommended to support management.
• If the cause is an infection: Treatment may involve antibiotics (for bacterial infections) or supportive care to help your body fight off the virus or parasite.
• If the cause is medication-related (e.g., NSAIDs): Your doctor may advise stopping or changing the medication under their supervision.
• Monitoring: After treatment begins, calprotectin levels may be rechecked to see if the inflammation is responding.

Important: Always work with a healthcare professional to determine the cause and appropriate treatment plan. Do not attempt to self-diagnose or self-treat based on a calprotectin test result.

When to Seek Urgent Medical Care

While a high calprotectin test result should always be discussed with a doctor, certain symptoms require prompt medical attention. Seek urgent care if you experience:

• Severe abdominal pain
• High fever
• Significant amounts of blood in your stool
• Dizziness, fainting, or signs of severe dehydration
• Unintentional and significant weight loss

These can be signs of a serious condition that needs immediate evaluation.

Understanding the Role of the Gut Microbiome

The community of microbes living in your gut, known as the microbiome, plays a key role in gut health and inflammation. An imbalance in this community, called dysbiosis, is often present alongside conditions that cause high calprotectin, such as IBD.

While microbiome testing cannot diagnose a disease, it can provide valuable context. For example, a test might show low microbial diversity or a reduction in beneficial bacteria that produce anti-inflammatory short-chain fatty acids. This information can help you and your healthcare provider understand the broader ecological state of your gut and inform supportive lifestyle strategies, such as dietary adjustments to increase fiber diversity.

Key Takeaways

• A high fecal calprotectin level indicates inflammation in the intestines.
• Common causes include IBD, infections, and diverticulitis.
• Colorectal cancer can be a cause, but calprotectin is not a cancer screening tool.
• Food is unlikely to cause a major spike, but long-term diet influences gut health.
• Treatment addresses the underlying cause of inflammation, not the high level itself.
• Always consult a doctor for interpretation of results and a management plan.

Questions and Answers

What is the normal range for fecal calprotectin?

Normal ranges can vary by lab, but generally, a level below 50 μg/g is considered normal in adults. Levels between 50-100 μg/g may be borderline, and results above 100-120 μg/g are typically considered elevated and suggestive of inflammation. Your lab report will provide its specific reference range.

Can a high calprotectin level be a false positive?

Yes, certain factors can cause a temporary elevation. These include recent use of nonsteroidal anti-inflammatory drugs (NSAIDs like ibuprofen), a recent gastrointestinal infection, or even vigorous exercise. This is why doctors consider the clinical context and may recommend a repeat test.

What is the difference between IBD and IBS in terms of calprotectin?

Inflammatory Bowel Disease (IBD), including Crohn's and ulcerative colitis, involves chronic inflammation, so calprotectin is usually high. Irritable Bowel Syndrome (IBS) is a functional disorder without visible inflammation, so calprotectin levels are typically normal. This difference makes the test very useful for distinguishing between the two.

How long does it take for calprotectin to go down?

It depends on the cause and treatment. After successful treatment for an infection or an IBD flare, levels can decrease within several weeks. Doctors often use repeat tests to monitor response to therapy.