title: Low faecal haemoglobin concentration potentially rules out significant colorectal disease.
abstract: OBJECTIVE
  The study aimed to determine whether faecal haemoglobin (Hb) concentration can assist in deciding who with lower abdominal symptoms will benefit from endoscopy.
  
  
  METHODS
  Faecal Hb concentrations were measured on single samples from 280 patients referred for lower gastrointestinal tract endoscopy from primary care in NHS Tayside who completed a faecal immunochemical test (FIT) for Hb and underwent subsequent endoscopy.
  
  
  RESULTS
  Among 739 invited patients, FIT and endoscopy were completed by 280 (median age 63 (18-84) years; 59.6% women), with a median time between FIT and endoscopy of 9 days. Six (2.1%) participants had cancer, 23 (8.2%) had high-risk adenoma (HRA) (more than three adenomas or any > 1 cm), 31 (11.1%) low-risk adenoma (LRA) and 26 (9.3%) inflammatory bowel disease (IBD) as the most serious diagnosis. Those with cancer had a median faecal Hb of > 1000 ng Hb/ml buffer. Those with cancer + HRA + IBD had a median faecal Hb concentration of 75 ng Hb/ml buffer (95% CI 18-204), which was significantly higher than that of all remaining participants without significant colorectal disease (P < 0.0001). Using a cut-off faecal Hb concentration of 50 ng Hb/ml buffer, negative predictive values of 100.0%, 94.4%, 93.4% and 93.9% were found for cancer, HRA, LRA and IBD. Patients with reasons for referral other than rectal bleeding and family history did not have high faecal Hb concentrations.
  
  
  CONCLUSIONS
  Faecal Hb concentration measurements have considerable potential to contribute to reducing unnecessary endoscopy for the majority of symptomatic patients.
authors.affiliation: Scottish Bowel Screening Centre, Kings Cross Hospital, Dundee, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: McDonald
authors.forename: J
authors.initials: J
authors.lastname: Digby
authors.forename: C
authors.initials: C
authors.lastname: Innes
authors.forename: J A
authors.initials: JA
authors.lastname: Strachan
authors.forename: F A
authors.initials: FA
authors.lastname: Carey
authors.forename: R J C
authors.initials: RJ
authors.lastname: Steele
authors.forename: C G
authors.initials: CG
authors.lastname: Fraser
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003108:Colonic Diseases / Q000175:diagnosis*; D003113:Colonoscopy; D005243:Feces / Q000737:chemistry*; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D012002:Rectal Diseases / Q000175:diagnosis*; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D006454:Hemoglobins