title: Toward Worldwide Hepcidin Assay Harmonization: Identification of a Commutable Secondary Reference Material.
abstract: Absolute plasma hepcidin concentrations measured by various procedures differ substantially, complicating interpretation of results and rendering reference intervals method dependent. We investigated the degree of equivalence achievable by harmonization and the identification of a commutable secondary reference material to accomplish this goal.
  
  
  
  We applied technical procedures to achieve harmonization developed by the Consortium for Harmonization of Clinical Laboratory Results. Eleven plasma hepcidin measurement procedures (5 mass spectrometry based and 6 immunochemical based) quantified native individual plasma samples (n = 32) and native plasma pools (n = 8) to assess analytical performance and current and achievable equivalence. In addition, 8 types of candidate reference materials (3 concentrations each, n = 24) were assessed for their suitability, most notably in terms of commutability, to serve as secondary reference material.
  
  
  
  Absolute hepcidin values and reproducibility (intrameasurement procedure CVs 2.9%-8.7%) differed substantially between measurement procedures, but all were linear and correlated well. The current equivalence (intermeasurement procedure CV 28.6%) between the methods was mainly attributable to differences in calibration and could thus be improved by harmonization with a common calibrator. Linear regression analysis and standardized residuals showed that a candidate reference material consisting of native lyophilized plasma with cryolyoprotectant was commutable for all measurement procedures. Mathematically simulated harmonization with this calibrator resulted in a maximum achievable equivalence of 7.7%.
  
  
  
  The secondary reference material identified in this study has the potential to substantially improve equivalence between hepcidin measurement procedures and contributes to the establishment of a traceability chain that will ultimately allow standardization of hepcidin measurement results.
authors.affiliation: Department of Laboratory Medicine and.
authors.forename: Lisa N
authors.initials: LN
authors.lastname: van der Vorm
authors.affiliation: Department of Health Evidence, Radboud University Medical Center, Nijmegen, the Netherlands;
authors.forename: Jan C M
authors.initials: JC
authors.lastname: Hendriks
authors.affiliation: Department of Laboratory Medicine and Hepcidinanalysis.com, Nijmegen, the Netherlands;
authors.forename: Coby M
authors.initials: CM
authors.lastname: Laarakkers
authors.affiliation: Department of Laboratory Medicine and.
authors.forename: Siem
authors.initials: S
authors.lastname: Klaver
authors.affiliation: MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK, and Blood Theme, NIHR Oxford Biomedical Research Centre, Oxford, UK;
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Armitage
authors.affiliation: Corgenix Medical Corporation, Broomfield, CO;
authors.forename: Alison
authors.initials: A
authors.lastname: Bamberg
authors.affiliation: Department of Laboratory Medicine and.
authors.forename: Anneke J
authors.initials: AJ
authors.lastname: Geurts-Moespot
authors.affiliation: Department of Medicine, University of Verona, Verona, Italy;
authors.forename: Domenico
authors.initials: D
authors.lastname: Girelli
authors.affiliation: DRG Instruments, Marburg, Germany;
authors.forename: Matthias
authors.initials: M
authors.lastname: Herkert
authors.affiliation: Helsinki University Central Hospital, Laboratory Division HUSLAB, Helsinki, Finland;
authors.forename: Outi
authors.initials: O
authors.lastname: Itkonen
authors.affiliation: Eli Lilly and Company, Indianapolis, IN;
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Konrad
authors.affiliation: Division of Advanced Medicine, Medical Research Institute, Kanazawa Medical University, Ishikawa, Japan;
authors.forename: Naohisa
authors.initials: N
authors.lastname: Tomosugi
authors.affiliation: Intrinsic LifeSciences, La Jolla, CA;
authors.forename: Mark
authors.initials: M
authors.lastname: Westerman
authors.affiliation: Institute of Pharmaceutical Sciences, King's College London, London, UK;
authors.forename: Sukhvinder S
authors.initials: SS
authors.lastname: Bansal
authors.affiliation: Department of Medicine, University of Verona, Verona, Italy;
authors.forename: Natascia
authors.initials: N
authors.lastname: Campostrini
authors.affiliation: MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK, and Blood Theme, NIHR Oxford Biomedical Research Centre, Oxford, UK;
authors.forename: Hal
authors.initials: H
authors.lastname: Drakesmith
authors.affiliation: Department of Analytical Pharmaceutical Chemistry, Institute of Pharmacy, University of Liège, Liège, Belgium;
authors.forename: Marianne
authors.initials: M
authors.lastname: Fillet
authors.affiliation: Intrinsic LifeSciences, La Jolla, CA;
authors.forename: Gordana
authors.initials: G
authors.lastname: Olbina
authors.affiliation: MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK, and Blood Theme, NIHR Oxford Biomedical Research Centre, Oxford, UK;
authors.forename: Sant-Rayn
authors.initials: SR
authors.lastname: Pasricha
authors.affiliation: Corgenix Medical Corporation, Broomfield, CO;
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Pitts
authors.affiliation: Eli Lilly and Company, Indianapolis, IN;
authors.forename: John H
authors.initials: JH
authors.lastname: Sloan
authors.affiliation: Department of Diagnostics and Public Health, University of Verona, Italy;
authors.forename: Franco
authors.initials: F
authors.lastname: Tagliaro
authors.affiliation: Department of Clinical Chemistry, Queen Beatrix Hospital, Winterswijk, the Netherlands.
authors.forename: Cas W
authors.initials: CW
authors.lastname: Weykamp
authors.affiliation: Department of Laboratory Medicine and Hepcidinanalysis.com, Nijmegen, the Netherlands; dorine.swinkels@radboudumc.nl.
authors.forename: Dorine W
authors.initials: DW
authors.lastname: Swinkels
mesh_terms: D064790:Clinical Laboratory Services / Q000592:standards*; D064451:Hepcidins / Q000097:blood*; D006801:Humans; D007120:Immunochemistry; D007391:International Cooperation; D016014:Linear Models; D012015:Reference Standards
chemical_list: D064451:Hepcidins