title: Unbound iron binding capacity (UIBC) as a test for empty iron stores--results from the HUNT Study.
abstract: BACKGROUND
  When s-iron and s-transferrin are used to diagnose empty iron stores, the measurements are usually combined in the calculation of s-transferrin saturation. This may not be the best way to utilize the information in s-iron and s-transferrin, as s-transferrin alone has a better diagnostic accuracy than s-transferrin saturation. We suggest that unbound iron binding capacity (UIBC), which is s-total iron binding capacity (2 times s-transferrin) minus s-iron could be used for diagnosing empty iron stores.
  
  
  METHODS
  To test this hypothesis, we used ROC curve analysis to compare the diagnostic accuracy of s-iron, s-transferrin, s-transferrin saturation and s-UIBC in diagnosing empty iron stores in 3029 women of childbearing age. Empty iron stores were defined as s-ferritin less than 10 μg/L or less than 15 μg/L.
  
  
  RESULTS
  At both definitions of empty iron stores s-UIBC had a better diagnostic accuracy than the other tests, with area under the ROC curve of 0.80-0.87. This was also the trend in a subpopulation of 172 anemic women, where the area under the ROC curve of s-UIBC was 0.92.
  
  
  CONCLUSIONS
  When diagnosing empty iron stores calculation of s-UIBC is a better way to utilize the information in s-iron and s-transferrin than is calculation of s-transferrin saturation.
authors.affiliation: Department of Clinical Chemistry, Trondheim University Hospital, Trondheim, Norway. arne.aasberg@stolav.no
authors.forename: Arne
authors.initials: A
authors.lastname: Åsberg
authors.forename: Ketil
authors.initials: K
authors.lastname: Thorstensen
authors.forename: Berit
authors.initials: B
authors.lastname: Borch-Iohnsen
mesh_terms: D000328:Adult; D019540:Area Under Curve; D002624:Chemistry, Clinical / Q000379:methods*; D005260:Female; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008875:Middle Aged; D009664:Norway; D011485:Protein Binding; D012372:ROC Curve; D014168:Transferrin / Q000378:metabolism; D055815:Young Adult
chemical_list: D014168:Transferrin; D007501:Iron