Evaluations of LDL-C and VLDL-C levels calculated by friedewald, Martin-Hopkins and Sampson equations at different triacylglycerol levels, by nuclear magnetic resonance spectrophotometry (NMR)

Introduction: Low-density lipoprotein cholesterol (LDL-C) is one of the most important preventable risk factors for cardiovascular disease (CVD). Its impact on clinical management has made the measurement of LDL-C and its accuracy even more important. Although the Friedewald equation has been widely used for nearly 50 years, its use in satiety, LDL-C<70 mg/dL and TG>400 mg/dL has been shown to give erroneous results. Therefore, new equations that can replace this equation in the calculation of LDL-C levels have been developed and have been included in the literature. Objective: The aim of this study was to evaluate the performance of enzymatic colorimetric method and equations by comparing with NMR reference method in individuals with different lipid content. In addition, it is aimed to find the method that determines the LDL-C level most accurately and to adapt it to automated systems. Materials and Methods: Very low density lipoprotein cholesterol (VLDL-C) and LDL-C results obtained by Nuclear Magnetic Resonance (NMR) Spectrophotometry, one of the alternative reference methods, were compared with the results obtained by enzymatic colorimetric method, Friedewald, Martin Hopkins, Extended Martin Hopkins and Sampson equations in 160 individuals with different lipid levels (especially triglyceride and LDL-C levels). Materials and Methods: Very low density lipoprotein cholesterol (VLDL-C) and LDL-C results obtained by Nuclear Magnetic Resonance (NMR) Spectrophotometry, one of the alternative reference methods, were compared with the results obtained by enzymatic colorimetric method, Friedewald, Martin Hopkins, Extended Martin Hopkins and Sampson equations in 160 individuals with different lipid levels (especially triglyceride and LDL-C levels). Results: When VLDL-C levels were evaluated, VLDLKeM and VLDLKM had the closest results to the NMR method, whereas LDL-C levels were evaluated by LDLKF and LDLKS methods. In addition, a significant difference was observed between the levels of LDLKeM, LDLKM methods. Conclusion and Recommendations: NMR technique provides valuable results in the development and routine use of appropriate algorithms that can provide more accurate results in obtaining VLDL-C and LDL-C levels considering different serum lipid levels. Since the performance of the equations differs at different triacylglycerol (TG) levels, it is recommended to develop algorithms according to TG levels and adapt them to automated systems. Key Words: Friedewald, LDL Cholesterol, Martin Hopkins, Nükleer Magnetic Resonance, Sampson