fecal calprotectin

 Q: 28 years old male is admitted to ICU with hypovolemic shock due to severe diarrhea. All workup for infectious causes is negative. GI service ordered fecal calprotectin. What is the efficacy of this test in severe diarrhea? 

 Answer:  Calprotectin is a zinc and calcium-binding protein. It is derived from neutrophils and monocytes, and a marker of neutrophil activity, particularly in mucosal inflammation. It has a very good negative value in diarrhea of undetermined etiology. If negative, inflammatory Bowel Disease (IBD) is unlikely as a cause of diarrhea. This test is also valuable as it correlates with the endoscopic disease activity of IBD and can further differentiate between active and inactive IBD. 

This test is not a gold standard and should be used with other laboratory and fecal tests such as fecal lactoferrin, and colonoscopy. 

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References:

1.  Schoepfer AM, Beglinger C, Straumann A, et al. Fecal calprotectin correlates more closely with the Simple Endoscopic Score for Crohn's disease (SES-CD) than CRP, blood leukocytes, and the CDAI. Am J Gastroenterol 2010; 105:162. 

2. Lobatón T, López-García A, Rodríguez-Moranta F, et al. A new rapid test for fecal calprotectin predicts endoscopic remission and postoperative recurrence in Crohn's disease. J Crohns Colitis 2013; 7:e641. 

3. D'Haens G, Ferrante M, Vermeire S, et al. Fecal calprotectin is a surrogate marker for endoscopic lesions in inflammatory bowel disease. Inflamm Bowel Dis 2012; 18:2218. 

4. Mosli MH, Zou G, Garg SK, et al. C-Reactive Protein, Fecal Calprotectin, and Stool Lactoferrin for Detection of Endoscopic Activity in Symptomatic Inflammatory Bowel Disease Patients: A Systematic Review and Meta-Analysis. Am J Gastroenterol 2015; 110:802.