Diagnosis and inflammation

A noninvasive option to differentiate IBD and IBS

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are both common and difficult to differentiate. Because both are distinct conditions with contrasting treatment strategies, distinguishing between the two is essential in patients who present with symptoms that generate clinical suspicion.

Calprotectin testing

Calprotectin, an indirect marker of intestinal inflammation, is a first-line testing option that can help differentiate between IBD and IBS.

  • Measures levels of calcium-binding proteins in fecal material as part of the diagnostic evaluation
  • Eliminates the need for additional invasive procedures or imaging studies
  • Reduces costs for patients and improves compliance related to fasting, bowel preparation, and sedation

Key testing

Calprotectin and Inflammatory Bowel Disease

The differential diagnosis for inflammatory bowel disease includes irritable bowel syndrome. The clinical presentation is similar, but IBD is an inflammatory disease and IBS is a noninflammatory disease. View this "Hot Topic" to learn about testing for IBD and IBS.

Serologic testing for Crohn’s disease and ulcerative colitis

Many commercial laboratories advocate much wider application of laboratory testing for the diagnosis of Crohn’s disease and ulcerative colitis, including serologic evaluations, genetic testing, and inflammatory marker quantitation. However, peer-reviewed literature only supports the use of three serologic tests and in limited applications for IBD. Mayo Clinic Laboratories’ tests exclude results that lack clinical relevance, minimizing additional test-related costs and leaving room for physician interpretation based on individual patients and medical assessments.

At Mayo Clinic Laboratories, serologic testing for IBD is used only when diagnosis made through flexible sigmoidoscopy or colonoscopy with mucosal biopsies and radiographic studies don’t clearly differentiate between ulcerative colitis and Crohn’s disease.

Our serology panel, which is based on significant peer-reviewed literature, examines only the characteristic patterns of antibodies with demonstrated clinical utility:

  • Saccharomyces cerevisiae antibodies, IgA
  • Saccharomyces cerevisiae antibodies, IgG
  • Neutrophil specific antibodies (perinuclear anti-neutrophilic cytoplasmic antibody — pANCA)

Beyond the test result

Our data-driven evaluation for IBD diagnosis provides in-depth analysis with detailed reports that include only relevant information, which helps contextualize results and provide clarity on disease presence. This approach provides ordering physicians the autonomy to make a diagnosis based on patient-specific factors.

Key testing

Inflammatory Bowel Disease

In this “Test in Focus” episode of the  "Answers From the Lab" podcast, Melissa Snyder, Ph.D., explains how IBDP2, when used after first-line testing has failed, can distinguish between ulcerative colitis and Crohn’s disease.

Mucosal healing provides better outcomes

A focus on mucosal healing reduces the need for steroids and risk of hospitalization and surgery. Unfortunately, complete mucosal healing can be hard to achieve, and agreement has not yet been reached on how much improvement is required for better outcomes.

The CALM trial1 from 2018 found that an approach geared toward reducing inflammatory markers of calprotectin and serum CRP, in addition to symptom reduction in patients with Crohn’s disease, improved mucosal healing and led to better clinical and endoscopic outcomes than a conventional approach.

Benefits of this approach over other noninvasive tests for mucosal healing:

  • All markers are clinically actionable
  • More cost-effective than using larger panels
  • Validated in a peer-reviewed study

Learn more about how to order these evaluations at your institution.


  1. Colombel JF, Panaccione R, Bossuyt P, et al. Effect of tight control management on Crohn’s disease (CALM): a multicentre, randomised, controlled phase 3 trial. Lancet. 2018 Dec 23;390(10114):2779-2789.