A simple turbidimetric assay designed for the routine screening well as therapeutic monitoring of native LDL particles

We describe the development and performance of a homogeneous assay for the direct turbidimetric determination of LDL particles in human serum. The ass ay is bused upon the specific agglutination of LDL pal-tides by the polyani on PAMPS. The co-agglutination of VLDL is avoided by the addition of a zwit terionic detergent. Yielding results within 10 min, the assay requires only a small sample volume taken directly from primary serum tubes, i.e., no pr etreatment of the sample is necessary. It can be easily applied to routine clinical chemistry analyzers. The results are highly correlated with LDL ch olesterol determinations by ultracentrifugation (r>0.95) and dextran sulfat e precipitation (r>0.95), but an increased recovery of small, high density LDL particles is observed, which more adequately reflects the atherogenic r isk of LDL. The assay provides excellent intra- and inter-assay CVs in the range of 0.6-1.6 and 1.7-2.4%, respectively, on Roche Diagnostics/Hitachi a nalyzers. The method is well suited to the high-throughput screening of LDL cholesterol levels. (C) 2001 Elsevier Science B.V. All rights reserved.