Should we routinely measure low-density and high-density lipoprotein subclasses?

Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) plasma populations are composed of heterogeneous subfractions that are different in size, density and protein/lipid content. There is increasing evidence that small, dense LDL particles are strongly associated with higher cardiovascular disease risk. Similarly, several studies have investigated whether smaller HDL particles are more protective than their larger counterparts and more recent findings suggest that small, dense HDL has significantly higher atheroprotective activity than larger HDL. Yet, certain impairments of the protein/lipid content in small, dense HDL may decrease its antiatherogenic capacity or even induce pro-atherogenic properties. Therefore, it seems that the small, dense phenomenon applies to both LDL and HDL particles. Measurement of LDL and HDL cholesterol concentrations has proven clinical utility, while the usefulness of LDL and HDL subclasses determination in clinical practice offers grounds for further exploration. However, LDL and HDL particles characterisation requires either special equipment or a lengthy analytical time and is, therefore, still unsuitable for general clinical use. It remains to be established whether lipoprotein subclasses should be analyzed in routine practice, although their assessment in high-risk subjects could be recommended.