[Evaluation of LDL-cholesterol measurement]

As a result of increased recognition of elevated LDL-cholesterol (LDL-C) as a risk for ischemic heart disease, the necessity for LDL-C measurement emerged in clinical laboratories. Consequently various LDL-C measurement methods were developed. The objective of the present review article is to compare and to evaluate the characteristics of various methods for LDL-C measurement. Because LDL is a particle defined by its density, ultracentrifugation method; beta-quantification is currently considered the reference method, but it is a time-consuming and expensive technique. The evaluation by Friedewald's equation is simple and applicable to the vast majority of normolipidemic samples. LDL-C measurement by electrophoresis provides an evaluation of LDL along with other lipoproteins. Homogeneous assays have the advantage of obviating the need for pretreatment of samples, and this is suitable for online performance, requiring only a few microliters of sample. Generally, there is little disagreement between methods in LDL-C data of normolipidemic samples. However, when the sample is from patients with dyslipidemia, there may be disagreement in LDL-C results between methods and the reason for this phenomena has been discussed. At the moment, the method for LDL-C measurement at each clinical laboratory has to be selected by adequately balancing demands, costs and benefits.