title: Re-assessment of the cut-off levels of Carbohydrate Deficient Transferrin (CDT) for automated immunoassay and multi-capillary electrophoresis for application in a forensic context.
abstract: BACKGROUND
  The determination of Carbohydrate Deficient Transferrin (CDT) in a forensic context should be based on the use of a screening technique followed, for the "positive samples", by a confirmatory technique. The aim of this study was to compare the two most used automated screening methods for CDT analysis, immuno-nephelometric assay (INA) and multi-capillary electrophoresis (mCE), with a validated HPLC procedure, used as confirmation test, in order to re-evaluate the cut-off concentrations of the screening methods.
  
  
  METHODS
  195 serum samples underwent CDT analysis by using the N Latex CDT direct immuno-nephelometric assay, the multicapillary system Capillarys™ and an anion exchange HPLC method with UV-visible detection at 460nm developed and validated at our laboratories. Statistical analyses were performed by using Bland-Altman plots and ROC curves.
  
  
  CONCLUSIONS
  The 95% limits of agreement were ±0.94% when comparing INA and HPLC and ±0.60% when comparing mCE and HPLC. The ROC analysis of both INA and mCE, using HPLC as the reference method, showed that no false negative results were found when the cut-off was fixed to 1.2% for mCE and to 2.3% for INA.
  
  
  CONCLUSIONS
  The study showed a good agreement among CDT determinations carried out either with mCE or INA or HPLC. However, the usual cut-offs of both mCE (1.3%) and INA (2.5%) should be lowered to minimize false negatives at the screening analysis.
authors.affiliation: Department of Public Health and Community Medicine, Unit of Forensic Medicine, University of Verona, Verona, Italy. federica.bortolotti@univr.it
authors.forename: Federica
authors.initials: F
authors.lastname: Bortolotti
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Trevisan
authors.forename: Rocco
authors.initials: R
authors.lastname: Micciolo
authors.forename: Luisa
authors.initials: L
authors.lastname: Canal
authors.forename: Anthula
authors.initials: A
authors.lastname: Vandoros
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Palmbach
authors.forename: Franco
authors.initials: F
authors.lastname: Tagliaro
mesh_terms: D001331:Automation; D001774:Blood Chemical Analysis / Q000379:methods*; D019075:Electrophoresis, Capillary; D044707:Forensic Sciences; D057166:High-Throughput Screening Assays / Q000592:standards*; D006801:Humans; D007118:Immunoassay; D012372:ROC Curve; D014168:Transferrin / Q000031:analogs & derivatives* / Q000032:analysis
chemical_list: D014168:Transferrin; C056759:carbohydrate-deficient transferrin