Measurements of lipids levels in blood are frequently used to assess the risk of future heart disease. The most commonly used measurements are total cholesterol, triglycerides and high density lipoprotein cholesterol (HDL-C). These numbers are then used to calculate low density lipoprotein cholesterol (LDL-C), which has been found to be strongly correlated with the risk of heart disease.
LDL-P measures the actual number of LDL particles (particle concentration). LDL-P may be a stronger predictor of cardiovascular events than LDL-C. Low LDL-P is a much stronger predictor of low risk than low LDL-C. In fact, about 30 – 40% of those with low LDL-C may have elevated LDL-P. Therefore you can have low LDL-C but still be at risk for heart disease, particularly if your LDL-P is elevated. Discordance is considered present if LDL-C differs from LDL-P.
LDL-C is a measure of the cholesterol mass within LDL-particles. LDL-C only indirectly reflects the atherogenic potential of LDL particles. ApoB and LDL-P on the other hand reflect the number of atherogenic particles, with no mention of cholesterol mass. ApoB and LDL-P are believed to be better risk predictors than LDL-C.
Many recent studies have looked into the importance of LDL-particle size. Studies show that people whose LDL particles are predominantly small and dense, have a threefold greater risk of coronary heart disease. Furthermore, the large and fluffy type of LDL may be protective.
Sometimes it is difficult to understand the difference between LDL-C and LDL-P and how particle size comes into the picture. It is quite likely that LDL particle number and size will be used more often in the future to assess risk. Therefore I decided to share with you four slides I often use to simplify these issues. In the slides LDL lipoprotein is presented as trucks carrying sand (cholesterol).
Hope you enjoy the slides although you may find my chemistry to be on preschool level.