Keywords
low-density lipoprotein cholesterol
Friedewald equation
homogeneous methods
total error
How to Cite
Abstract
Cardiovascular disease is the leading cause of death worldwide. In this sense, the reduction of cardiovascular risk, which is directly related to the concentration of cholesterol associated with lowdensity lipoproteins (LDL-C), is the main therapeutic target. Although there are direct homogeneous methods to measure LDL-C, many laboratories estimate LDL-C by using Friedewald equation. The aim of this work was to evaluate the correlation between the methodologies mentioned above and
their compliance with international quality requirements. The study included 1549 outpatients. Blood samples were obtained by venipuncture. Triglycerides (TG) and total cholesterol were measured by standard methods. High-density lipoprotein cholesterol was measured by a homogeneous method and LDL-C was measured by a homogeneous method and calculated using Friedewald equation. To assess the analytical performance of both methods, the coefficient of variation, bias, and total error were calculated and correlations between methods were evaluated at different TG concentrations. Only the homogeneous method showed acceptable analytical performance. Based on our results, we propose that LDL-C should be measured by the homogeneous method and not estimated by Friedewald equation, at least when TG values are higher than 200 mg/dl.