A Boy With Frequent Diarrhea: Differentiating IBS From IBD

Lindsey G. Albenberg, DO; Wenjing Zong, MD


March 18, 2019

Editorial Collaboration

Medscape &

Serologic Testing in Pediatric IBD

Although IBD serology panels are widely available and may seem attractive, GI specialists do not recommend them or find them helpful when included as part of a referral. Studies have suggested that serologic markers such as anti-neutrophil cytoplasmic antibodies and anti- Saccharomyces cerevisiae antibody titers are not useful for screening purposes. The diagnosis of IBD is based on endoscopic, radiologic, and histopathologic criteria. Anti-neutrophil cytoplasmic antibodies and anti-Saccharomyces cerevisiae antibody have low sensitivity, which limits their use in IBD screening. Therefore, they currently have no role as the initial screening test.[1,2,3]

Laboratory Evaluations to Consider

Screening laboratories may include complete blood count with differential, comprehensive metabolic panel, erythrocyte sedimentation rate, C-reactive protein, and infectious stool studies. Abnormalities could include leukocytosis, anemia, and thrombocytosis. Hypoalbuminemia is very common in Crohn disease. There may also be elevations in erythrocyte sedimentation rate and C-reactive protein. It is important to remember that up to 20% of children with IBD have normal C-reactive protein and/or erythrocyte sedimentation rate.[4] Normal inflammatory markers should not preclude referral to a GI specialist if the history is otherwise concerning. Stool studies can reveal infectious causes of diarrhea. However, it is important to note that patients with IBD can experience a higher rate of Clostridium difficile infection without the typical risk factors.[4,5]

Stool studies. These may include:

  • C difficile

  • General bacterial stool culture (which should include Salmonella, Shigella, Escherichia coli, Yersinia, and Campylobacter)

  • Optional: stool viral panel, ova and parasites, Cryptosporidium, stool calprotectin

Clinically, the concentration of calprotectin in feces is used as a noninvasive measure of neutrophilic infiltrate in the bowel mucosa, and thus intestinal inflammation. There is no universally agreed -on cutoff value for normal and abnormal. However, a recent retrospective case-control study identified a cut point of between 200 and 300 μg/g as optimal to distinguish the presence or absence of endoscopically detectable mucosal inflammation.[6] Fecal calprotectin is usually covered by insurance with a diagnosis code of diarrhea when it is ordered with the purpose of determining which children with gastrointestinal symptoms or growth failure require further investigation.

Case Continued: GI Studies

The patient underwent magnetic resonance enterography to evaluate the small bowel, which was normal. He then underwent endoscopic evaluation of his upper and lower GI tract.

Figure 2. Photo showing inflamed colonic mucosa on colonoscopy.

Colonoscopy showed continuous erythema and friable mucosa extending from the rectum to the hepatic flexure. The biopsies showed signs of chronic inflammation including crypt architectural distortion. There were no granulomas.