LDL cholesterol estimation in patients with the metabolic syndrome

BACKGROUND: The Friedewald formula (LDL-F) for the estimation of low-density lipoprotein (LDL) cholesterol concentrations is the most often used formula in clinical trials and clinical practice. However, much concern has been raised as to whether this formula is applicable in all patient populations such as the presence of chylomicronaemia and/or hypertriglyceridaemia. The aim of the present study was to evaluate various LDL cholesterol calculation formulas as well as LDL cholesterol levels provided by the Lipoprint LDL System (LDL-L) in patients with the metabolic syndrome (MetSyn). RESULTS: LDL-F showed significant differences from other formulas in the total cohort, as well as in MetSyn individuals. This was not the case in nonMetSyn subjects, where LDL-F did not differ with other formulas, with the exception of one formula (LDL by Planella, LDL-P). The bias between LDL-F and other LDL estimation formulas were significantly higher in MetSyn subjects compared to nonMetSyn individuals, except for LDL-L which produced similar bias with LDL-F in both study groups. CONCLUSION: LDL-F seems to exhibit some limitations as far as the calculation of LDL-C levels in patients with the MetSyn is concerned. LDL-L might be more accurate in MetSyn subjects, but so far its use is limited for the estimation of small, dense LDL (sdLDL) cholesterol levels and mean LDL particle size for research purposes only

Qualitative and quantitative disturbances of lipid and lipoprotein metabolism in people with the metabolic syndrome

Over the last few years, there has been increasing interest regarding the constellation of metabolic disturbances that constitute the metabolic syndrome (MetSyn) which significantly increase the cardiovascular risk. These disturbances include an atherogenic lipid profile, increased blood pressure measurements and an altered carbohydrate metabolism. The prevalence of the MetSyn is rising rapidly worldwide, mostly due to the increased prevalence of obesity. The term HTGW syndrome is used for the identification of individuals with inceased TG levels and elevated WC. These individuals are characterised by the presence of the atherogenic metabolic triad, i.e. elevated serum levels of insulin, apoB and sdLDL particles. Moreover, individuals with the HTGW syndrome are at increased risk for cardiovascular disease (CVD) and new onset diabetes mellitus. Several clinical studies (both in healthy subjects as well as in patients with known CVD) have shown that increased Lp-PLA2 mass and/or activity is associated with elevated vascular risk. The purpose of the present study was to determine in detail the lipid profile of subjects with the MetSyn or the HTGW syndrome and compare it with that of individuals who did not fulfill the criteria for the diagnosis of the above mentioned syndromes. We emphasised on the evaluation of the sdLDL-C levels and the mean and peak LDL particle diameter using a new electrophoretic method (Lipoprint LDL System). Moreover, we assessed Lp-PLA2 activity and mass in total plasma, in HDL, as well as in lipoprotein subfractions. According to our results, MetSyn individuals exhibit increased levels of sdLDL-C and decreased mean and peak LDL particle size compared with subjects that do not fulfill the MetSyn criteria. SdLDL-C levels increase and LDL particle size decreases as the number of the criteria fulfilled rise. The major determinant of these disturbances is the concentration of TG in serum. Individuals with the HTGW syndrome are characterised by increased levels of VLDL-C and sdLDL-C and decreased LDL particle size compared with patients without the HTGW syndrome. SdLDL-C concentration increased and LDL particle size decreased with increasing serum levels of TG and WC measurements. Women with TG levels ?112 mg/dL and WC ?84.5 cm were 4-times more likely to exhibit the metabolic triad compared with women with one or none of these two parameters above the proposed cut-off points. Total plasma activity (but not mass) is the second best predictor of the presence of sdLDL particles in plasma (following serum TG levels). Finally, most of Lp-PLA2 mass is delivered on sdLDL particles. However, the enzyme activity is much less than that expected of its mass. In conclusion, MetSyn and HTGW individuals are characterised by a more atherogenic profile compared with subjects who do not fulfill the criteria for the diagnosis of these two syndromes. Total plasma Lp-PLA2 is the second best predictor of the presence of sdLDL particles, after serum TG levels