CardioMet
Published January 16, 2023 | Version v1
Journal article Open

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

Authors/Creators

  • 1. Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center
  • 2. Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig
  • 3. Division of Laboratory Sciences, Centers for Disease Control and Prevention
  • 4. Department of Laboratory Medicine and Pathology, University of Washington
  • 5. Siemens Healthcare Diagnostics Products GmbH
  • 6. French Institute of Health and Medical Research (Inserm), Université Paris Descartes
  • 7. Department of Genetics and Pharmacology, Institute of Genetic Epidemiology, Medical University of Innsbruck
  • 8. Laboratoire National de Métrologie et d'Essais
  • 9. European Commission, Joint Research Centre
  • 10. Division of Molecular Biology and Biochemistry, Gottfried Schatz Research Center (for Cell Signaling, Metabolism and Aging), Medical University of Graz
  • 11. Department of Genetics and Pharmacology, Institute of Genetic, Epidemiology, Medical University of Innsbruck
  • 12. Roche Diagnostics GmbH

Description

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, MSbased
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).

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