Calprotectin Stool Test in Children: Levels, Causes & Next Steps

A calprotectin stool test is a simple, non-invasive test that helps doctors assess whether there is inflammation in a child's intestines. It's often used when children have persistent gastrointestinal symptoms like chronic diarrhea, abdominal pain, or blood in stool. This article provides a comprehensive guide for parents, explaining how the test works, what the results mean—including what level might be concerning—the potential causes of high calprotectin, and the typical next steps following a test.

At a Glance: Key Points About Calprotectin Testing in Children

• What it is: A stool test that measures calprotectin, a protein released by white blood cells during intestinal inflammation.
• Main use: To help distinguish between inflammatory conditions (like IBD) and non-inflammatory functional issues (like IBS).
• Concerning levels: Vary by age and lab, but values above 250 µg/g in older children often warrant further investigation.
• Common causes of high results: Inflammatory Bowel Disease (IBD), infections, certain medications, and other gut irritants.
• Next steps: A high result typically leads to repeat testing, additional blood work, imaging, or a referral to a specialist.

What Is a Calprotectin Stool Test?

A calprotectin stool test measures the amount of a protein called calprotectin in a child's stool. Calprotectin is released by neutrophils, a type of white blood cell that rushes to the site of inflammation. When the intestinal lining is inflamed, these cells release calprotectin, which then passes into the stool. By measuring its concentration, doctors can get an indirect measure of inflammation within the gut.

This test is particularly valuable in pediatrics because it is non-invasive. Instead of needing more invasive procedures right away, it helps doctors decide if further investigation is necessary. It's important to understand that an elevated calprotectin level signals inflammation but does not diagnose a specific disease on its own.

What Level of Calprotectin Is Concerning in Children?

There is no single universal "normal" level, as reference ranges can vary between laboratories. More importantly, what is considered a concerning level depends heavily on the child's age.

• Infants and Toddlers (under 4 years): Naturally have higher baseline calprotectin levels due to gut and immune system development. Levels can be significantly higher than in adults without indicating disease.
• Older Children and Adolescents: Values below 50 micrograms per gram (µg/g) are generally considered normal. Levels between 50-250 µg/g are often viewed as borderline or mildly elevated. Results persistently above 250-300 µg/g are typically considered concerning and strongly suggest significant intestinal inflammation that requires further medical evaluation.

Key Takeaway: Always interpret results using the reference range provided by the laboratory and in consultation with your child's doctor, who will consider their age and specific symptoms.

What Can Cause Fecal Calprotectin to Be High?

A high fecal calprotectin result indicates inflammation in the intestines. Several conditions and factors can cause this elevation.

Disease-Related Causes

• Inflammatory Bowel Disease (IBD): This includes Crohn's disease and ulcerative colitis, which are chronic conditions causing inflammation in the digestive tract.
• Bacterial or Viral Infections: Gastroenteritis (a "stomach bug") is a common cause of temporary spikes in calprotectin.
• Other Inflammatory Conditions: Certain autoimmune conditions can also affect the gut.

Non-Disease-Related Causes

• Medications: Non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen, can irritate the gut lining and temporarily increase calprotectin.
• Recent Gastrointestinal Illness: Levels can remain elevated for a short time after an infection has resolved.

Can Food Cause High Calprotectin?

Food itself is not a direct cause of high calprotectin levels. There is no strong evidence that specific foods directly and significantly elevate calprotectin in a way that mimics disease-related inflammation. However, in children with underlying food allergies (like cow's milk protein allergy) or celiac disease, the inflammatory response triggered by eating problematic foods can lead to an elevated calprotectin level. The inflammation caused by the immune reaction is what drives the increase, not the food itself.

What Is the Treatment for High Calprotectin Levels?

It's crucial to understand that doctors treat the underlying cause of the inflammation, not the high calprotectin level itself. The test result is a signal that guides the next steps. There is no "treatment" to lower calprotectin directly.

When a child has a high calprotectin result, a doctor will typically:

1. Review Symptoms and History: Correlate the result with the child's symptoms, growth charts, and family history.
2. Repeat the Test: Especially if there was a recent illness, to see if the elevation is persistent.
3. Order Additional Tests: This may include blood tests (to check for anemia or other inflammation markers), stool cultures (to rule out infections), or tests for celiac disease.
4. Refer to a Specialist: A pediatric gastroenterologist may be consulted for further evaluation, which could include imaging or endoscopic procedures.
5. Initiate Treatment: If a condition like IBD is diagnosed, treatment will focus on controlling inflammation with medications and dietary management.

When Is Calprotectin Testing Used in Children?

Doctors typically consider this test when a child has persistent or concerning symptoms that suggest possible gut inflammation, such as:

• Chronic diarrhea (lasting more than 2-4 weeks)
• Persistent abdominal pain, especially pain that wakes the child at night
• Blood or mucus in the stool
• Unexplained weight loss or poor growth (faltering growth)
• Family history of Inflammatory Bowel Disease (IBD)

The goal is to help determine if these symptoms are likely due to inflammation (which would require further workup) or a functional issue like irritable bowel syndrome (IBS), where inflammation is not typically present.

The Role of the Gut Microbiome

The gut microbiome—the community of bacteria and other microbes living in the digestive tract—plays a key role in gut health and immune function. An imbalance in the microbiome (dysbiosis) can sometimes be associated with inflammation. While a calprotectin test measures inflammation, microbiome testing (which is educational and not diagnostic) can provide insight into the microbial balance. For some families, this complementary information can help inform discussions with a healthcare provider about diet and lifestyle strategies to support overall gut health. Microbiome testing should always be used alongside, not instead of, standard medical care.

Frequently Asked Questions (FAQs)

What level of calprotectin is concerning?

In older children, levels above 250-300 µg/g are generally considered concerning and warrant further investigation. For infants and toddlers, normal ranges are much higher, so results must be interpreted using age-specific reference ranges from the lab.

What is the treatment for high calprotectin levels?

There is no direct treatment for a high level. The focus is on identifying and treating the underlying cause of the inflammation, such as an infection or a chronic condition like IBD. This process is guided by a pediatrician or gastroenterologist.

What can cause fecal calprotectin to be high?

Common causes include Inflammatory Bowel Disease (IBD), bacterial or viral infections (like gastroenteritis), use of NSAID medications, and in infants, sometimes just normal developmental processes.

Can food cause high calprotectin?

Food does not directly cause a high calprotectin level. However, if a child has an immune-mediated reaction to a food (as in food allergies or celiac disease), the resulting inflammation can lead to an elevated calprotectin level.

Is calprotectin testing commonly used in children?

Yes, it is a widely used and accepted non-invasive tool in pediatrics to screen for intestinal inflammation when symptoms are persistent and concerning.

Does a normal calprotectin result rule out all problems?

No. A normal result makes significant inflammation less likely, but it does not rule out functional disorders like irritable bowel syndrome (IBS) or food intolerances.

Conclusion

The calprotectin stool test is a valuable first step in evaluating a child for possible intestinal inflammation. Understanding what the test measures, how to interpret the results in the context of your child's age, and knowing the potential causes of a high reading can empower you to have more informed discussions with your healthcare provider. Remember, the test is a piece of the puzzle, and any concerning results should be followed up with a thorough medical evaluation to determine the best course of action for your child's health.

References & Further Reading

• van Rheenen PF, Van de Vijver E, Fidler V. Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: systematic review and diagnostic meta-analysis. BMJ. 2010;341:c3369. Link
• Henderson P, et al. The diagnostic accuracy of fecal calprotectin during the investigation of suspected pediatric inflammatory bowel disease. Am J Gastroenterol. 2012;107(6):941–949. Link
• ESPGHAN Working Groups. Role of noninvasive markers and intestinal ultrasound for monitoring IBD in children. J Pediatr Gastroenterol Nutr. 2021;72(5):795–806. Link
• Frías-Lamas E, et al. Fecal calprotectin in healthy children aged 1–4 years. J Pediatr Gastroenterol Nutr. 2015;61(1):107–111. Link
• Assa A, et al. Fecal calprotectin in pediatric inflammatory bowel disease: Back to basics and clinical applications. World J Gastroenterol. 2021;27(9):908–931. Link