Faecal calprotectin

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Measurement of faecal calprotectin is a biochemical test for intestinal inflammation, including inflammatory bowel disease. Under specific clinical scenario, the test may eliminate the need for invasive colonoscopy or radio-labelled white cell scanning.

Structure and function[edit]

Calprotectin is a 36kDa calcium and zinc binding protein expressed by the gene S100 calcium-binding protein A8, S100A8. It accounts for 30 to 40% of neutrophils' cytosol. In vitro studies show it has bacteriostatic and fungistatic properties. It is resistant to enzymatic degradation, and can be easily measured in faeces.[1]

Use as a surrogate marker[edit]

Reference ranges for calprotectin
Patient age Upper limit Unit
2–9 years 166[2] µg/g of faeces
10–59 years 51[2]
≥ 60 years 112[2]

The main diseases that cause an increased excretion of faecal calprotectin are infectious colitis,[3] Crohn's disease, ulcerative colitis, and neoplasms (cancer).

Inflammatory bowel diseases (IBD) are a group of conditions that cause a pathological inflammation of the bowel wall. Neutrophils influx into the bowel lumen as a result of the inflammatory process. Measurement of faecal calprotectin has been shown to be strongly correlated with 111-indium-labelled leucocytes - considered the gold standard measurement of intestinal inflammation.[4] Levels of faecal calprotectin are normal in patients with irritable bowel syndrome (IBS).[5]

Although a relatively new test, faecal calprotectin is regularly used as indicator for IBD during treatment and as diagnostic marker.[6]

Specific indications for measuring calprotectin are in:[1]

  • Distinguishing inflammatory bowel disease (IBD) from functional bowel disease (IBS), and thus avoid the need for invasive tests such as colonoscopy.
  • Assessing efficacy of IBD treatments.
  • Predicting relapses or flares of IBD.
  • Offer an alternate diagnostic test for patients phobic of needles or endoscopy.

False-positive measurements[edit]

Although faecal calprotectin correlates significantly with disease activity in people with confirmed IBD,[7] faecal calprotectin can be false-positive in some conditions. Most importantly, intake of proton pump inhibitors (e.g. omeprazole) is associated with significantly elevated calprotectin values.[8]

References[edit]

  1. ^ a b Tibble J, Teahon K, Thjodleifsson B, Roseth A, Sigthorsson G, Bridger S et al. (2000). "A simple method for assessing intestinal inflammation in Crohn's disease". Gut 47 (4): 506–13. PMC 1728060. PMID 10986210. 
  2. ^ a b c Joshi S, Lewis SJ, Creanor S, Ayling RM (2009). "Age-related faecal calprotectin, lactoferrin and tumour M2-PK concentrations in healthy volunteers". Annals of Clinical Biochemistry 47 (Pt 3): 259–263. doi:10.1258/acb.2009.009061. PMID 19740914. 
  3. ^ Chen CC, Huang JL, Chang CJ, Kong MS (2012). "Fecal calprotectin as a correlative marker in clinical severity of infectious diarrhea and usefulness in evaluating bacterial or viral pathogens in children". J. Pediatr. Gastroenterol. Nutr. 55 (5): 541–7. doi:10.1097/MPG.0b013e318262a718. PMID 22699836. 
  4. ^ Costa F, Mumolo MG, Bellini M, Romano MR, Ceccarelli L, Arpe P et al. (2003). "Role of faecal calprotectin as non-invasive marker of intestinal inflammation". Dig Liver Dis 35 (9): 642–7. PMID 14563186. 
  5. ^ Costa F, Mumolo MG, Ceccarelli L, Bellini M, Romano MR, Sterpi C et al. (2005). "Calprotectin is a stronger predictive marker of relapse in ulcerative colitis than in Crohn's disease". Gut 54 (3): 364–8. doi:10.1136/gut.2004.043406. PMC 1774401. PMID 15710984. 
  6. ^ van Rheenen PF, Van de Vijver E, Fidler V (2010). "Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: diagnostic meta-analysis". BMJ 341: c3369. PMC 2904879. PMID 20634346. Lay summaryMedScape. 
  7. ^ D'Haens G, Ferrante M, Vermeire S, Baert F, Noman M, Moortgat L et al. (2012). "Fecal calprotectin is a surrogate marker for endoscopic lesions in inflammatory bowel disease". Inflamm. Bowel Dis. 18 (12): 2218–24. doi:10.1002/ibd.22917. PMID 22344983. 
  8. ^ Poullis A, Foster R, Mendall MA, Shreeve D, Wiener K (2003). "Proton pump inhibitors are associated with elevation of faecal calprotectin and may affect specificity". Eur J Gastroenterol Hepatol 15 (5): 573–4; author reply 574. PMID 12702920.