title: Disparity of serum transferrin receptor measurements among different assay methods.
abstract: OBJECTIVE
  To highlight differences in the quantification of transferrin receptor (TfR) concentration (a reliable index of iron deficiency) between three different assay methods.
  
  
  METHODS
  Methods comparison of TfR measurements in 'elevated' and 'normal' human sera using the Ramco, Quantikine and 'Lab' assays.
  
  
  METHODS
  The Hospital for Sick Children, Toronto, Ontario, Canada.
  
  
  METHODS
  Pooled TfR for elevated and normal human sera obtained from the Ramco TfR assay kit.
  
  
  METHODS
  Differences between TfR concentrations in normal and elevated samples and repeatability for each assay method and limits of agreement in TfR quantification between assay methods.
  
  
  RESULTS
  The mean TfR concentrations for the elevated reference serum samples was higher than the normal reference samples within each individual assay (P < 0.001); however, measurement agreement between methods was poor.
  
  
  CONCLUSIONS
  Recognition of the relative differences in the values obtained from each of the assays should affect the interpretation of TfR concentration as an index of iron deficiency.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Research Institute, The Hospital for Sick Children, ON, Canada.
authors.forename: G S
authors.initials: GS
authors.lastname: Yeung
authors.forename: J C
authors.initials: JC
authors.lastname: Kjarsgaard
authors.forename: S H
authors.initials: SH
authors.lastname: Zlotkin
mesh_terms: D006801:Humans; D007118:Immunoassay; D007124:Immunoenzyme Techniques; D011786:Quality Control; D011933:Reagent Kits, Diagnostic; D011990:Receptors, Transferrin / Q000097:blood*; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results
chemical_list: D011933:Reagent Kits, Diagnostic; D011990:Receptors, Transferrin