Disparate LDL phenotypic classification among 4 different methods assessing LDL particle characteristics

BACKGROUND: Our study seeks to clarify the extent of differences in analytical results, from a clinical perspective, among 4 leading technologies currently used in clinical reference laboratories for the analysis of LDL subfractions: gradient gel electrophoresis (GGE), ultracentrifugation-vertical auto profile (VAP), nuclear magnetic resonance (NMR), and tube gel electrophoresis (TGE). METHODS: We collected 4 simultaneous blood samples from 40 persons (30 males and 10 females) to determine LDL subclasses in 4 different clinical reference laboratories using different methods for analysis. LDL subfractions were assessed according to LDL particle size and the results categorized according to LDL phenotype. We compared results obtained from the different technologies. RESULTS: We observed substantial heterogeneity of results and interpretations among the 4 methods. Complete agreement among methods with respect to LDL subclass phenotyping occurred in only 8% (n = 3) of the persons studied. NMR and GGE agreed most frequently at 70% (n = 28), whereas VAP matched least often. CONCLUSIONS: As measurement of LDL subclasses becomes increasingly important, standardization of methods is needed. Variation among currently available methods renders them unreliable and limits their clinical usefulness.