Introduction: In inflammatory bowel diseases (IBD) diarrhea can be caused by exacerbation and/or infectious agents. Fecal calprotectin (FC) is a well-established biomarker of intestinal inflammation in IBD. However, its usefulness in depiction of IBD exacerbation from infectious diarrhea is limited. The value of fecal pyruvate kinase isoenzyme type 2 (M2-PK) in this application remains unknown.
Aim: To compare the performance of M2-PK and FC in discriminating between diarrhea caused by IBD and infectious agents.
Materials and methods: One hundred three patients were enrolled for the study, including 32 with ulcerative colitis (UC), 21 with Crohn's disease (CD), 29 with acute diarrhea caused by rotavirus (AD-RV), and 21 with acute diarrhea caused by Salmonella enteritidis (AD-SE). M2-PK and FC were measured using ELISA. Areas under receiver operating characteristic curves (AUCs), sensitivities and specificities for both tests in distinguishing between patient subgroups with moderate to severe UC and CD from AD-RV and AD-SE were calculated.
Results: Differences in AUCs between M2-PK and FC for distinguishing UC [CD] from AD-RV were -0.06 (p < 0.028) [-0.10 (p < 0.0018)] and for differentiating UC [CD] from AD-SE were 0.03 (NS) [-0.19(p < 0.0011)].M2-PK sensitivities and specificities in distinguishing UC [CD] from AD-RV were 75.0%[71.4%] and 89.7% [89.7%] and for differentiation of UC [CD] from AD-SE were 56.3% [71.4%] and 95.2[57.1%].
Conclusions: The performance of M2-PK in distinguishing between children with moderate-to-severe IBD and patients with infectious gastroenteritis was inferior to FC. Neither test had sensitivity ands pecificity sufficient for everyday clinical application.