Testing
Serum and plasma Lp(a) measurements agree closely, ARIC study of 100 participants (J Clin Lipidol 2026)
Original title: Correlation between serum and plasma lipoprotein(a) measurements: ARIC study
ARIC (Atherosclerosis Risk in Communities) study comparing Lp(a) measured in EDTA plasma versus serum using the same validated, isoform-insensitive assay in 100 participants sampled across age, sex, race and Lp(a) level (0 to above 200 nmol/L). Serum and plasma Lp(a) correlated excellently (Spearman's r=0.99). Deming regression gave a slope of 1.05 (95% CI 1.03-1.08) and an intercept of 0.26 nmol/L (95% CI -1.97 to 2.41). Bland-Altman analysis found no statistically significant mean difference between serum and plasma (+7.7 nmol/L, 95% CI -16.7 to 32.0). The authors conclude serum and plasma can be used interchangeably for Lp(a) measurement, supporting pooling of data from both specimen types.
Original abstract
Background: Lipoprotein(a) [Lp(a)] is recommended for atherosclerotic cardiovascular disease (ASCVD) risk assessment and is targeted by new drugs in development. However, the association of Lp(a) with ASCVD was identified from epidemiologic studies that typically used plasma samples.
Objective: To determine the agreement between serum- and plasma-based Lp(a) measurements.
Methods: We measured Lp(a) in both EDTA plasma and serum using the same validated, isoform-insensitive assay in 100 Atherosclerosis Risk in Communities participants equally distributed across age, sex, race, and Lp(a) levels (0 to >200 nmol/L). We assessed correlation (Spearman), mean differences, and bias (Deming regression).
Results: The correlation between serum and plasma was excellent (Spearman's r = 0.99). Deming regression yielded a slope of 1.05 (95% CI 1.03, 1.08) and an intercept of 0.26 nmol/L (95% CI -1.97, +2.41). Bland-Altman analysis identified no statistically significant mean difference (serum minus plasma: +7.7 nmol/L [95% CI -16.7, +32.0]).
Conclusion: We demonstrated excellent agreement between serum and plasma Lp(a), supporting the use of either specimen for Lp(a) measurement and pooling data from both sources.
Summary written by lp-a.org from the published abstract; figures as published. Page updated 17 August 2026. Methods.