title: Anemia is a poor predictor of iron deficiency among toddlers in the United States: for heme the bell tolls.
abstract: BACKGROUND
  Many toddlers in the United States have their hemoglobin (Hb) measured periodically. Is this worthwhile?
  
  
  OBJECTIVE
  To determine if the presence of anemia correctly diagnoses iron deficiency (ID) and if the absence of anemia correctly rules out ID in young children.
  
  
  METHODS
  An analysis of data from the US National Health and Nutrition Examination Survey III (1988-1994) was performed. Subjects were children 12 to 35 months old for whom complete blood counts and cardinal measures of iron nutrition (ferritin, transferrin saturation, and free erythrocyte protoporphyrin) were reported.
  
  
  RESULTS
  In the US National Health and Nutrition Examination Survey III, the prevalence of ID ranged from 6% to 18% in various subpopulations of toddlers. In the general population, the positive predictive value of Hb concentration ([Hb]) <110 g/L for ID was 29% (95% confidence interval [CI]: 20-38%), and the sensitivity was 30% (95% CI: 20-40%). Changing the diagnostic cutoff point to [Hb] <107 g/L resulted in a positive predictive value of 38% (95% CI: 24-52%) but lowered the sensitivity to 15% (95% CI: 7-22%).
  
  
  CONCLUSIONS
  ID remains common in the United States. In agreement with other reports, anemia in toddlers in developed countries is more likely to be due to causes other than ID. Conversely, most children with ID are not anemic. Many false-positive and false-negative results render the measurement of Hb a screening test of relatively little value. The current detection strategy needlessly treats and retests many children without ID and leaves many iron-deficient toddlers unattended.
authors.affiliation: Department of Pediatrics, Contra Costa Regional Medical Center and Health Centers, 2500 Alhambra Ave, Martinez, California 94553, USA. kcwhite@ucdavis.edu
authors.forename: Keith C
authors.initials: KC
authors.lastname: White
mesh_terms: D000740:Anemia / Q000453:epidemiology; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000175:diagnosis* / Q000208:ethnology; D002675:Child, Preschool; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007223:Infant; D000090463:Iron Deficiencies; D009749:Nutrition Surveys; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology
chemical_list: D006454:Hemoglobins