Non-HDL Cholesterol

Into the Spotlight

The elevated coronary heart disease (CHD) risk affecting patients with type 2 diabetes may be attributed to a combined dyslipidemia characterized by elevated triglycerides, reduced HDL cholesterol, small dense LDL particles (independent of the LDL cholesterol level), elevated triglyceride-rich remnant lipoproteins (TGRLs), and/or elevated apolipoprotein B (apoB) levels (1). All of these features have individually been implicated as contributors to CHD. Some reports suggest that the combined dyslipidemia may confer a higher magnitude of risk than elevated LDL cholesterol alone (2).

The role of triglycerides as a risk factor has been controversial. Much of its risk may be attributed to the associated low HDL cholesterol level, along with contributions from all of the other related variables. Although triglycerides do appear to be an independent risk factor (3), they likely act only as a marker for these associated features. The measurement of apoB has been advocated as an alternative index (4). Since each LDL particle contains a single apoB molecule, the apoB level reflects particle number, thus not only accounting for both remnant and LDL particles but also the density of particles when expressed in relation to particle cholesterol content. Despite these advantages, even the global standardization of apoB assays (5) has not made it routinely available to the clinician. This may be in part due to a general unfamiliarity with its interpretation outside of the research setting and because existing guidelines do not take advantage of the information it imparts. Its cost relative to its potential advantages for clinical decision-making also has not been adequately explored.

Existing guidelines, however, do take advantage of non–HDL cholesterol as an index of risk associated with this combined dyslipidemia. The recognition of this index is not new; this “beta” lipoprotein cholesterol fraction has been associated with increased CHD mortality in population-based studies that …