title: Faecal calprotectin: factors affecting levels and its potential role as a surrogate marker for risk of development of Crohn's Disease.
abstract: BACKGROUND
  Faecal calprotectin (FC) is one of the most widely used non-invasive tests for the diagnosis and assessment of Crohn's disease (CD) activity. Despite this, factors other than disease activity which affect levels have not been extensively reviewed. This is of importance when using FC in the diagnostic setting but also may be of utility in studying the aetiology of disease.
  
  
  OBJECTIVE
  Our review outlines environmental risk factors that affect FC levels influencing diagnostic accuracy and how these may be associated with risk of developing CD. FC as a surrogate marker could be used to validate risk factors established in case control studies where prospective studies are not feasible. Proof of this concept is provided by our identification of obesity as being associated with elevated FC, our subsequent confirmation of obesity as risk factor for CD and the subsequent verification in prospective studies, as well as associations of lack of physical activity and dietary fibre intake with elevated FC levels and their subsequent confirmation as risk factors in prospective studies.
  
  
  CONCLUSIONS
  We believe that FC is likely to prove a useful surrogate marker for risk of developing CD. This review has given a theoretical basis for considering the epidemiological determinants of CD which to date has been missing.
authors.affiliation: Department of Gastroenterology, Croydon University Hospital, 530 London Road, Surrey, CR7 7YE, UK.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mendall
authors.affiliation: Department of Gastroenterology, Blackshaw Road, London, SW17 0QT, UK.
authors.forename: Derek
authors.initials: D
authors.lastname: Chan
authors.affiliation: Department of Colorectal Surgery, St George's Hospital, Blackshaw Road, London, SW17 0QT, UK.
authors.forename: Roshani
authors.initials: R
authors.lastname: Patel
authors.affiliation: Department of Colorectal Surgery, St George's Hospital, Blackshaw Road, London, SW17 0QT, UK. dkumar@sgul.ac.uk.
authors.forename: Devinder
authors.initials: D
authors.lastname: Kumar
mesh_terms: D015415:Biomarkers / Q000032:analysis; D003424:Crohn Disease / Q000209:etiology*; D005243:Feces / Q000737:chemistry*; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis*; D009765:Obesity / Q000150:complications / Q000378:metabolism; D012307:Risk Factors
chemical_list: D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex
keywords: Calprotectin; Crohn’s disease; Diet; Environment; Surrogate marker