Development of an LC-MRM-MS-Based Candidate Reference Measurement Procedure for Standardization of Serum Apolipoprotein (a) Tests

Clinical Chemistry, vol. 69, pp. 251–261

Abstract

BACKGROUND: Medical results generated by European CE Marking for In Vitro Diagnostic or in-house tests should be traceable to higher order reference measurement systems (RMS), such as International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)-endorsed reference measurement procedures (RMPs) and reference materials. Currently, serum apolipoprotein (a) [apo(a)] is recognized as a novel risk factor for cardiovascular risk assessment and patient management. The former RMS for serum apo(a) is no longer available; consequently, an International System of Units (SI)-traceable, ideally multiplexed, and sustainable RMS for apo(a) is needed. METHODS: A mass spectrometry (MS)-based candidate RMP (cRMP) for apo(a) was developed using quantitative bottom-up proteomics targeting 3 proteotypic peptides. The method was provisionally validated according to ISO 15193 using a single human serum based calibrator traceable to the former WHO-IFCC RMS. RESULTS: The quantitation of serum apo(a) was by design independent of its size polymorphism, was linear from 3.8 to 456 nmol/L, and had a lower limit of quantitation for apo(a) of 3.8 nmol/L using peptide LFLEPTQADIALLK. Interpeptide agreement showed Pearson Rs of 0.987 and 0.984 for peptides GISSTVTGR and TPENYPNAGLTR, and method comparison indicated good correspondence (slopes 0.977, 1.033, and 1.085 for LFLEPTQADIALLK, GISSTVTGR, and TPENYPNAGLTR). Average within-laboratory imprecision of the cRMP was 8.9%, 11.9%, and 12.8% for the 3 peptides. CONCLUSIONS: A robust, antibody-independent, MS-based cRMP was developed as higher order RMP and an essential part of the apo(a) traceability chain and future RMS. The cRMP fulfils predefined analytical performance specifications, making it a promising RMP candidate in an SI-traceable MS-based RMS for apo(a).

Authors 19

1. L. Renee Ruhaak corresponding Aachen Department of Clinical Chemistry Laboratory Medicine

   Leiden University Medical Center

   Affiliation as printed

   Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center , Leiden , The Netherlands

2. Fred P.H.T.M. Romijn Aachen Department of Clinical Chemistry Laboratory Medicine

   Leiden University Medical Center

   Affiliation as printed

   Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center , Leiden , The Netherlands

3. Ilijana Begcevic Brkovic

   University Hospital Leipzig

   Affiliation as printed

   Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig , Leipzig , Germany

4. Zsusanna Kuklenyik

   Centers for Disease Control and Prevention

   Affiliation as printed

   Division of Laboratory Sciences, Centers for Disease Control and Prevention , Atlanta, GA , USA

5. Julia Dittrich

   University Hospital Leipzig

   Affiliation as printed

   Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig , Leipzig , Germany

6. Uta Ceglarek

   University Hospital Leipzig

   Affiliation as printed

   Division Clinical Mass Spectrometry of the German Society of Clinical Chemistry and Laboratory Medicine (DGKL) , Berlin , Germany

   Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig , Leipzig , Germany

7. Andrew N. Hoofnagle

   University of Washington

   Affiliation as printed

   Department of Laboratory Medicine and Pathology, University of Washington , Seattle, WA , USA

8. Harald Althaus

   Siemens Healthineers (Germany)

   Affiliation as printed

   Siemens Healthcare Diagnostics Products GmbH , Marburg , Germany

9. Eduardo Anglés‐Cano

   Inserm · Université Paris Descartes

   Affiliation as printed

   French Institute of Health and Medical Research (Inserm), Université Paris Descartes , Paris , France

10. Stefan Coassin

    Innsbruck Medical University · Universität Innsbruck

    Affiliation as printed

    Department of Genetics and Pharmacology, Institute of Genetic Epidemiology, Medical University of Innsbruck , Innsbruck , Austria

11. Vincent Delatour

    Laboratoire National de Métrologie et d'Essais

    Affiliation as printed

    Laboratoire National de Métrologie et d’Essais , Paris , France

12. Liesbet Deprez

    European Commission · Joint Research Center

    Affiliation as printed

    European Commission, Joint Research Centre , Geel , Belgium

13. Ioannis Dikaios

    European Commission · Joint Research Center

    Affiliation as printed

    European Commission, Joint Research Centre , Geel , Belgium

14. Gerhard Max Kostner

    Medical University of Graz

    Affiliation as printed

    Division of Molecular Biology and Biochemistry, Gottfried Schatz Research Center (for Cell Signaling, Metabolism and Aging), Medical University of Graz , Graz , Austria

15. Florian Kronenberg

    Innsbruck Medical University · Universität Innsbruck

    Affiliation as printed

    Department of Genetics and Pharmacology, Institute of Genetic Epidemiology, Medical University of Innsbruck , Innsbruck , Austria

16. Alicia N. Lyle

    Centers for Disease Control and Prevention

    Affiliation as printed

    Division of Laboratory Sciences, Centers for Disease Control and Prevention , Atlanta, GA , USA

17. Urban Prinzing
    Affiliation as printed

    Roche Diagnostics GmbH , Penzberg , Germany

18. Hubert W. Vesper

    Centers for Disease Control and Prevention

    Affiliation as printed

    Division of Laboratory Sciences, Centers for Disease Control and Prevention , Atlanta, GA , USA

19. Christa M. Cobbaert Aachen Department of Clinical Chemistry Laboratory Medicine

    Leiden University Medical Center

    Affiliation as printed

    Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center , Leiden , The Netherlands