title: Faecal haemoglobin concentrations by gender and age: implications for population-based screening for colorectal cancer.
abstract: BACKGROUND
  Faecal immunochemical tests (FIT) are becoming widely used in colorectal cancer screening. Estimation of faecal haemoglobin concentration in a large group prompted an observational study on gender and age.
  
  
  METHODS
  A single estimate of faecal haemoglobin concentration was made using quantitative automated immunoturbidimetry. Potential reference intervals were calculated for men and women and for age quintiles according to the Clinical and Laboratory Standards Institute Approved Guideline. The percentages of positive results were calculated at a number of concentrations. The percentages of individuals who fell into different risk groups were assessed.
  
  
  RESULTS
  The 97.5 percentiles, potential upper reference limits, were 519 ng haemoglobin/mL (90% CI: 468-575) for men and 283 ng haemoglobin/mL (90% CI: 257-316) for women. Concentrations increased with age in both genders. Decision limits have advantages over reference intervals. At any cut-off concentration, more men are declared positive than women and more older people are declared positive than younger people. Future risk of neoplasia is higher in men than in women and in older people.
  
  
  CONCLUSIONS
  Faecal haemoglobin concentrations vary with gender and age. More tailored strategies are needed in screening programmes. Faecal haemoglobin concentration could be included in individual risk assessment scores. These data should assist in screening programme design.
authors.affiliation: Scottish Bowel Screening Centre, Kings Cross, Dundee, Scotland, UK.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: McDonald
authors.forename: Judith A
authors.initials: JA
authors.lastname: Strachan
authors.forename: Jayne
authors.initials: J
authors.lastname: Digby
authors.forename: Robert J C
authors.initials: RJ
authors.lastname: Steele
authors.forename: Callum G
authors.initials: CG
authors.lastname: Fraser
mesh_terms: D000367:Age Factors; D000368:Aged; D019963:Clinical Chemistry Tests / Q000592:standards*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005243:Feces / Q000737:chemistry*; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000592:standards*; D008875:Middle Aged; D012016:Reference Values; D012737:Sex Factors
chemical_list: D006454:Hemoglobins