Stool Testing for Pediatric Irritable Bowel Syndrome
In pediatric patients with suspected IBS, perform fecal calprotectin and celiac serology (IgA tissue transglutaminase with total IgA) as the primary stool and serologic screening tests, along with stool testing for infectious pathogens only if there is recent acute diarrhea or travel history. 1, 2
Core Recommended Tests
Fecal Calprotectin
- Fecal calprotectin should be measured in all pediatric patients with IBS-like symptoms to exclude inflammatory bowel disease (IBD). 1, 2 This is particularly critical because children often present with more extensive colitis than adults, and symptoms can overlap significantly between IBS and IBD. 3
- Use a cutoff of <100 μg/g to reliably indicate absence of mucosal inflammation in children with suspected IBS. 4
- The test performs with 94% sensitivity and 64% specificity for detecting intestinal inflammation in pediatric patients. 4
- Note that fecal calprotectin can be falsely elevated by NSAID use within the past 6 weeks, so document medication history. 5
Celiac Disease Screening
- Test IgA tissue transglutaminase (tTG) with total IgA level in all children presenting with IBS symptoms. 1, 2 This is a strong recommendation with moderate-quality evidence, as celiac disease commonly mimics IBS and has sensitivity >90%. 1
- For children with IgA deficiency, use IgG-based testing such as IgG-deamidated gliadin peptide or IgG-tTG. 1
Conditional Stool Testing
Infectious Pathogen Testing
- Test for Giardia specifically in children with IBS-diarrhea symptoms, as this is the most common parasitic cause of chronic diarrhea. 1
- Perform comprehensive stool culture for Campylobacter, Salmonella, and Shigella only if the child has recent acute diarrheal illness or travel to endemic areas. 1, 2
- Do not routinely test for ova and parasites beyond Giardia unless there is specific travel history to or recent immigration from high-risk areas. 1
C-Reactive Protein
- Consider checking CRP under specific circumstances when fecal calprotectin is borderline or unavailable, though this is a conditional recommendation. 2
- Be aware that approximately 20% of children with active Crohn's disease may have normal CRP levels, so normal inflammatory markers do not completely exclude IBD. 1
Tests NOT Recommended
Routine Pathogen Screening
- Do not perform routine stool testing for enteric pathogens in children with chronic IBS symptoms without recent acute illness or travel history. 2
- Avoid broad ova and parasite testing beyond Giardia screening. 1
Food Allergy/Intolerance Testing
- Do not routinely test for food allergies or intolerances through stool studies in pediatric IBS. 2
- Lactose breath testing may be considered only if the child consumes >280 ml of milk daily and belongs to high-risk ethnic groups, but this is not a stool test. 1
Small Intestinal Bacterial Overgrowth (SIBO)
- Do not test for SIBO in children with typical IBS symptoms, as hydrogen breath testing is not recommended. 1, 2
Important Clinical Context
Age-Specific Considerations
- Children under 6 years presenting with IBS-like symptoms require evaluation for primary immunodeficiency disorders before assuming functional disease. 3
- Very young children (<2 years) have wider normal ranges for fecal calprotectin, requiring higher thresholds for interpretation. 5
When to Pursue Further Investigation
- Perform colonoscopy only in children with alarm features such as:
Common Pitfalls to Avoid
- Do not rely on normal CRP alone to exclude IBD, as it lacks sensitivity in pediatric patients. 1
- Avoid over-testing with broad infectious panels in children with chronic symptoms lasting >4 weeks without acute illness. 2
- Do not perform ultrasound imaging, as it frequently detects incidental findings unrelated to IBS symptoms. 1
- Ensure constipation is ruled out before finalizing an IBS diagnosis, as this is a common mimic in children. 2