Evaluation of a new homogenous method for detection of small dense LDL cholesterol: Comparison with the LDL cholesterol profile obtained by density gradient ultracentrifugation

BackgroundSmall, dense LDL (sdLDL) are highly atherogenic, and evidence indicates that sdLDL are useful predictors of cardiovascular disease. We evaluated a homogeneous method for the quantitative determination of sdLDL cholesterol (sdLDL-C) and compared it to the LDL-cholesterol profile obtained by density gradient ultracentrifugation (DGUC).MethodssdLDL-C was measured in plasma and in lipoprotein fractions obtained by DGUC using the sdLDL-EX “Seiken” kit.ResultssdLDL-C was only present in dense or intermediate LDL fractions obtained by DGUC. Plasma sdLDL-C levels were inversely corelated to the LDL relative floatation rate. The proportion of LDL-C that is sdLDL-C increases as a function of LDL density from a median of 19% for very buoyant LDL to 91% for very dense LDL particles. Plasma sdLDL-C level was significantly correlated with plasma triglyceride (TG) (n = 840, rs = 0.710, p < 0.001). Among subjects with plasma TG > 150 mg/dl, 75% had sdLDL-C > 30 mg/dl, whereas among those with TG ≤ 150 mg/dl, only 17% had sdLDL-C > 30 mg/dl.ConclusionsThis precise and fully automated method for measuring plasma levels of sdLDL-C will allow the analysis of large number of samples in routine laboratories which will facilitate the evaluation of the clinical usefulness of sdLDL as a risk factor for CHD.