Current Understanding in the Measurement of Low Density Lipoprotein Cholesterol: A Comparison of Direct Measurement by Homogenous Assays versus Calculations

Abstract

Background: To compare the results obtained by direct homogenous assay for LDL-C to those obtained by Friedwalds and Anandrajas formulas with the assumption that the results obtained by direct assay are most accurate. This was a comparative study for the estimation of LDL-C using two different types of calculation formulas and direct estimation of LDL-C by homogenous method. Method: Serum Lipids and lipoproteins were measured in 505 fasting samples. Serum Total cholesterol was measured using CHOD-PAP method first described by Stadman on Siemens Dimensions Clinical Chemistry RXL Analyzer. Triglycerides were measured by Glycerol Phosphate peroxidase - PAP method. Direct LDL-C was measured by a homogenous assay by siemens diagnostics. A- HDL was measured by a homogenous method which uses PEG- cholesterol esterase using kit from siemens diagnostics. This was a comparative study for the estimation of LDL-C using two different types of calculation formulas and direct estimation of LDL-C by homogenous method. Results: A good correlation was found between D-LDL as compared to both F-LDL and A-LDL. Pearsons coefficient of correlation between F-LDL & D-LDL was 0.891 (p