Testing
Recalibrating five Lp(a) immunoassays against an IFCC mass-spectrometry reference sharply cuts inter-method variability, Japanese harmonization study finds (J Atheroscler Thromb 2025)
Original title: Harmonization of Lipoprotein(a) Immunoassays Using A Serum Panel Value Assigned with The IFCC-Endorsed Mass Spectrometry-Based Reference Measurement Procedure as A First Step Towards Apolipoprotein Standardization
This study tested whether harmonising Lp(a) immunoassays against a serum panel value assigned by the IFCC-endorsed mass-spectrometry-based reference measurement procedure (IFCC-MS-RMP) could resolve the long-standing inconsistency between Lp(a) immunoassays. Five Lp(a) immunoassays were measured in 40 CDC panel sera and 500 Japanese subjects from the Bunkyo Health Study; only the Roche assay was traceable to the WHO-IFCC reference material SRM2B. All immunoassays, including Roche's, correlated well with IFCC-MS-RMP in the CDC panel, and all correlated well with Roche's reagent in the Bunkyo samples (rs 0.986-0.998), though regression slopes ranged widely from 0.292 to 0.579, reflecting substantial baseline disagreement. After recalibrating with the CDC panel sera, Bunkyo Health Study Lp(a) results converted to IFCC-MS-RMP-equivalent values showed a marked reduction in inter-method coefficient of variation. The authors conclude harmonisation of Lp(a) measurement across five different immunoassays was achieved using this reference-calibrated approach, an important step toward standardised, comparable Lp(a) reporting.
Original abstract
Aim: Lipoprotein (a) [Lp(a)] is a well-established risk factor for cardiovascular disease independent of low-density lipoprotein-cholesterol (LDL-C). The Lp(a) concentrations were inconsistent between the immunoassays. This study aimed to investigate whether harmonization of Lp(a) measurements can be achieved using a serum panel value assigned with the IFCC-endorsed mass spectrometry-based reference measurement procedure (IFCC-MS-RMP).
Methods: We measured the Lp(a) concentrations using five Lp(a) immunoassays in 40 panel sera provided by the Centers for Disease Control and Prevention (CDC), and 500 Japanese subjects enrolled in the Bunkyo Health Study. Of the five immunoassays, only the Roche Lp(a) assay was traceable to the WHO-IFCC reference material SRM2B. Lp(a) concentrations in CDC samples were also determined by IFCC-MS-RMP, provisionally calibrated to SRM2B. Lp(a) concentrations were expressed in mass units (mg/dL) for most reagents, but in SI units (nmol/L) for Roche's reagent and IFCC-MS-RMP.
Results: In the CDC panel sera, all immunoassays, including Roche's reagent, showed good correlations with IFCC-MS-RMP. In the Bunkyo Health Study samples, all immunoassays showed good correlations with Roche's reagent (rs, 0.986-0.998) although the slopes of the regression lines ranged from 0.292 to 0.579. After recalibration with the CDC's panel sera, Lp(a) results of Bunkyo Health Study samples were converted to the equivalent values determined by the IFCC-MS-RMP, thus resulting in a marked reduction in the intermethod CV among the assays.
Conclusion: We achieved harmonization of Lp(a) measurements with five immunoassays using a serum panel value assigned with the IFCC-MS-RMP.
Summary written by lp-a.org from the published abstract; figures as published. Page updated 17 August 2026. Methods.