Two articles in this issue of The Journal1,2 examine prospectively whether smaller low-density lipoprotein (LDL) particle size predicts coronary heart disease (CHD) incidence. The heterogeneity of LDL particles with respect to size, density, and composition is well recognized. A predominance of small LDL particles in the plasma is often accompanied by hepatic overproduction of very low-density lipoproteins (VLDLs) and hypertriglyceridemia. Exchange of triglycerides from the VLDL core with cholesteryl esters from the LDL core and subsequent hydrolysis of the triglycerides result in smaller LDL particles. These smaller LDL particles are denser since they still contain the same amount of protein (apolipoprotein B [apo B]) as other LDL particles but a smaller amount of lipids, which are more buoyant. Thus, the LDL apo B level measures the number of LDL particles, while LDL cholesterol (LDL-C) is a measure which combines the number of particles and their cholesterol content.
Coresh J, Kwiterovich PO. Small, Dense Low-Density Lipoprotein Particles and Coronary Heart Disease RiskA Clear Association With Uncertain Implications. JAMA. 1996;276(11):914-915. doi:10.1001/jama.1996.03540110068034