Lipoprotein(a) immunoassays and their associations with coronary artery calcification and aortic valve calcification

Background Lp(a) causes atherosclerosis and degenerative aortic valve disease, but concerns have risen that mass- based assays may be affected by isoform sizes and provide inaccurate estimates of Lp(a) exposure. Methods We compared contemporary immunoturbidimetric assays reporting either mass-based (Randox) or molar- based (Roche) using data from 5,129 unselected participants from the prospective population-based Rotterdam Study cohort. We studied the association of both Lp(a) measurements with the burden of coronary artery calcium (CAC) and aortic valve calcification (AVC) in a random subset of participants who underwent cardiac CT. Results There was a near perfect linear correlation between Lp(a) concentrations from both immunoassays (R2 98.8%) with most pronounced differences apparent only at very high Lp(a) concentrations. Lp(a) concentrations were related with natural logtransformed Agatston scores (Randox standardized linear 9 0.1003, P = 5.6<middle dot>10-8; Roche standardized linear 9 0.1004, P = 5.4<middle dot>10-8). Lp(a) concentrations were strongly but similarly related to natural log-transformed AVC Agatston scores (Randox standardized linear 9 0.1525, P = 9.2<middle dot>10-16; Roche standardized linear 9 0.1539, P = 4.8<middle dot>10-16). Conclusion We demonstrate that these immunoassays provide interchangeable Lp(a) measurements, and that associations with CAC and AVC were near-identical. This provides opportunities to directly compare findings from research done with either immunoassay. Trial Registration The Rotterdam Study has been entered in the Netherlands National Trial Register and the WHO International Clinical Trials Registry Platform under shared catalog number NTR6831. (Am Heart J 2025;284:42-46.)