Harmonization of Liquid Chromatography-Tandem Mass Spectrometry Protein Assays

Abstract

Harmonization of diagnostic test results is fundamental to the effective use of laboratory testing in the diagnosis, treatment, and monitoring of disease. Formal approaches to harmonization and standardization provide a rigorous and high-quality roadmap to this end, although the formal harmonization process can be long and complex. In the meantime, more informal approaches to harmonization can provide a useful pathway to improved harmonization in the short term. Factors relevant to harmonization are discussed with particular attention to protein assays using LC-MS/MS. Published formal and informal harmonization projects are provided as examples, including lessons drawn from these projects.

Keywords: Harmonization; LC-MS/MS; Protein; Standardization.

Fig. 1.

Overview of a general approach to manage harmonization of a measurand. IVD, in vitro diagnostic; JCTLM, Joint Committee for Traceability of Laboratory Medicine. Greg Miller W, Myers GL, Lou Gantzer M, et al. Roadmap for Harmonization of Clinical Laboratory Measurement Procedures Clinical Chemistry 2011;57(8):1108–17; Reproduced with permission from the American Association for Clinical Chemistry.

Fig. 2.

General process for assessing and achieving harmonization (equivalency) of clinical laboratory measurement results. Greg Miller W, Myers GL, Lou Gantzer M, et al. Roadmap for Harmonization of Clinical Laboratory Measurement Procedures Clinical Chemistry 2011;57(8):1108–17; Reproduced with permission from the American Association for Clinical Chemistry.

Fig. 3.

Illustration of traceability chain for standardizing methods to an agreed-on absolute standard of accuracy. NMI, National Measurement Institute. (Data from International Organization for Standardization. (2003–2008). In vitro diagnostic medical devices – Measurement of quantities in biological samples – Metrological traceability of values assigned to calibrators and control materials (ISO 17511:2003). Retrieved from: https://www.iso.org/standard/30716.html)

Fig. 4.

Results from preliminary Tg harmonization study. (From Netzel BC, Grant RP, Hoofnagle AN. First steps toward harmonization of LC-MS/MS thyroglobulin assays: letter to the editor. Clin Chem 2015;62:1; with permission.)

Fig. 5.

Example of a decision matrix for choosing calibrators. Green check marks indicate an analytical consideration for which the given calibrator accounts for a given source of bias. iTRAQ, Isobaric tags for relative and absolute quantitation; N/A, not applicable; 18O-Oxygen-18; PTM, Post translational modification; SILAC, Stable Isotope Labeling by/with Amino acids in Cell culture; SIL,stable isotope labeled; TMT, Tandem Mass Tag.