Testing
A new formula corrects LDL cholesterol for lipoprotein(a) cholesterol content, eliminating negative values seen with the standard 30% assumption (Cardiovasc Drugs Ther 2024)
Original title: Quantification of LDL-Cholesterol Corrected for Molar Concentration of Lipoprotein(a)
Using 440 samples from 239 participants in the BANTING study, the authors derived a new formula for Lp(a) cholesterol (Lp(a) nmol/L x 0.077 = Lp(a)-C mg/dL) to correct LDL-C for Lp(a) content. With the conventional formula, which assumes Lp(a)-C is 30% of Lp(a) mass, about 7% of samples with low LDL-C produced negative corrected values; the new formula produced none. Among participants with the highest Lp(a)/apoB ratio (P<0.001) and smaller apolipoprotein(a) isoform size (P<0.006), the conventional formula significantly underestimated Lp(a)-corrected LDL-C, risking undertreatment. The new formula gives more reliable LDL-C estimates when Lp(a) is elevated.
Original abstract
Purpose: Cholesterol in lipoprotein(a) [Lp(a)-C] is commonly estimated as 30% of the measured Lp(a) mass. However, difficulties in the accurate measurement of Lp(a) mass, along with the inaccuracy of the 30% assumption, produce erroneous values when LDL-C is corrected for Lp(a) [LDL-CLp(a)corr]. Our aim was to develop a new formula for LDL-CLp(a)corr to reduce this error.
Methods: We developed a new formula to calculate Lp(a)-C from the molar measurement of Lp(a), which is Lp(a) nmol/L × 0.077 = Lp(a)-C mg/dL. The calculated Lp(a)-C is subtracted from LDL-C to obtain LDL-CLp(a)corr. The results obtained with our novel formula versus the conventional formula were compared in 440 samples from 239 participants enrolled in the BANTING study.
Results: With the conventional formula, approximately 7% of samples with low LDL-C resulted in negative LDL-CLp(a)corr values. With the new formula, no negative LDL-CLp(a)corr values occurred. Among groups with the highest Lp(a)/apoB ratio (p < 0.001) and smaller apolipoprotein(a) isoform size (p < 0.006), LDL-CLp(a)corr was significantly underestimated by the conventional formula, which may result in the undertreatment of some patients.
Conclusion: The new formula provides more reliable estimates of LDL-CLp(a)corr than the conventional formula.
Trial Registration: ClinicalTrials.gov NCT02739984.
Summary written by lp-a.org from the published abstract; figures as published. Page updated 18 August 2026. Methods.