LDL Particles Are Nonspherical: Consequences for Size Determination and Phenotypic Classification

The recent article by Ensign et al. (1), reporting on a disappointingly low agreement among 4 methods to assess LDL particle size and phenotypic classification, casts doubt on the utility of these techniques in clinical practice. A similar poor correlation ( r = 0.39) between LDL size measurements by nuclear magnetic resonance (NMR) and gradient gel electrophoresis (GGE) has been reported by Witte et al. in a study with 324 individuals (2). Ensign et al.(1) advocate a standardization program to reduce the lack of concordance between methods. In addition to standardization problems, however, there is another reason for the observed discrepancy that is not addressed in the Ensign paper and accompanying editorial; the assumption that LDL size is adequately described by a single variable, diameter.We would like to point out that this assumption may not be valid for LDL particle size. The situation is akin to …