title: Application of retinol-binding protein enzyme immunoassay to dried blood spots to assess vitamin A deficiency in a population-based survey: the Uganda Demographic and Health Survey 2006.
abstract: BACKGROUND
  Vitamin A deficiency is a public health problem in most developing countries. The technological challenges associated with the measurement of serum retinol have limited the epidemiologic assessment of vitamin A deficiency. The combination of retinol-binding protein (RBP) enzyme immunoassay and dried blood spots offers a rapid, inexpensive, and reliable tool for the population-level assessment of vitamin A deficiency in resource-poor settings.
  
  
  OBJECTIVE
  To report on the application of RBP enzyme immunoassay and dried blood spots to assess serum retinol concentrations as an indicator of vitamin A status in the Uganda Demographic and Health Survey 2006.
  
  
  METHODS
  A total of 5,642 capillary blood spot samples were collected by fingerprick onto filter paper cards from women (15-49 years) and children (6-59 months) in a representative probability sample of 9,864 households between May and October 2006. The cards were dried, packed individually with desiccant, and kept at 4 degrees C in a portable refrigerator in the field and at -20 degrees C in the laboratory. Prior to analysis, the RBP enzyme immunoassay was optimized with the use of matched serum and dried blood spots.
  
  
  RESULTS
  The correlation between RBP values determined by matching serum and dried blood spots was excellent (r = 0.79, p < .00001). The prevalence of vitamin A deficiency in women (RBP < 1.24 micromol/L) and children (RBP < 0.825 micromol/L) was 19.4% and 20.4%, respectively.
  
  
  CONCLUSIONS
  The combination of RBP enzyme immunoassay and dried blood spots is a simple, reliable, and cost-effective tool for the estimation of vitamin A deficiency in population-level surveys in resource-poor settings.
authors.affiliation: Department of Biochemistry, Makerere University, Kampala, Uganda. rbaingana@sci.mak.ac.ug
authors.forename: Rhona Kezabu
authors.initials: RK
authors.lastname: Baingana
authors.forename: Denis Kasozi
authors.initials: DK
authors.lastname: Matovu
authors.forename: Dean
authors.initials: D
authors.lastname: Garrett
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D002675:Child, Preschool; D005260:Female; D006306:Health Surveys; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D007223:Infant; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D015995:Prevalence; D012177:Retinol-Binding Proteins / Q000032:analysis* / Q000378:metabolism; D014454:Uganda / Q000453:epidemiology; D014801:Vitamin A / Q000097:blood*; D014802:Vitamin A Deficiency / Q000175:diagnosis* / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D012177:Retinol-Binding Proteins; D014801:Vitamin A