title: How often is a positive faecal occult blood test the result of coeliac disease?
abstract: OBJECTIVE
  It has been reported that occult gastrointestinal bleeding as detected by faecal occult blood (FOB) testing can occur in coeliac disease. This study examines whether a positive FOB is a feature of coeliac disease and whether FOB-positive subjects need investigation for coeliac disease.
  
  
  METHODS
  First, the records of patients on the Nottingham Register for Coeliac Disease were reviewed for positive FOB testing. Second, the Nottingham colorectal cancer screening trial database was also reviewed to examine how many coeliac patients on the Register had participated and to examine their FOB results. Finally, sera from 309 screening trial participants who were FOB-positive but had no colonic abnormality were screened for immunoglobulin A (IgA) gliadin and IgA endomysial and human tissue transglutaminase (tTG) IgA antibodies.
  
  
  RESULTS
  Five of 590 patients on the Register had had FOB tests at the time of diagnosis; four had positive tests during investigation of diarrhoea and/or anaemia. Of 21 patients on the Register who had participated in the colorectal cancer screening trial, one had a positive FOB test and was found to have a rectal tubulo-villous adenoma. Of the 309 FOB-positive patients, 7% (22 subjects) were positive for IgA gliadin antibodies, but none had IgA endomysial antibodies detected and two subjects had positive human tTG antibody assays for coeliac disease.
  
  
  CONCLUSIONS
  Occult gastrointestinal bleeding occurs in a small number of symptomatic coeliac disease patients before diagnosis, but is no more frequent in treated and undetected coeliac disease patients than in the general population. Unless there are other indications, coeliac disease does not need to be considered in the investigation of a positive FOB test.
mesh_terms: D000328:Adult; D000368:Aged; D002446:Celiac Disease / Q000175:diagnosis*; D015179:Colorectal Neoplasms / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009780:Occult Blood; D012042:Registries