Small Dense Low Density Lipoprotein Cholesterol, Paraoxonase 1 and Lipid Profile in Postmenopausal Women: Quality or Quantity?

BACKGROUND AND AIMS

Atherosclerosis, the root cause of cardiovascular disease (CVD), has a number of risk factors-some modifiable and some not. CVD increases in women particularly during the postmenopausal period. Small dense low-density lipoprotein (sdLDL), a subclass of LDL, is an important determinant of atherosclerosis in postmenopausal women. Paraoxonase1 (PON1) is a high-density lipoprotein (HDL)-associated enzyme that prevents oxidative modifications in LDL and HDL. With this background, we studied the sdLDL-C, PON1 and lipid profile in postmenopausal women to compare between quality and quantity of LDL.

METHODS

We studied 80 pre- and postmenopausal women (40/group). The following parameters were studied: lipid profile, sdLDL-C and PON1 levels. With proper statistical tools the correlation between these parameters was studied.

RESULTS

Postmenopausal women, in comparison with premenopausal women, have significantly increased levels of serum triglycerides and sdLDL-C and very-low-density lipoprotein cholesterol (VLDL-C) and significantly decreased levels of HDL-C and PON1. PON1 activity was negatively correlated with age, TC, TG, LDL-C and sdLDL-C (r = -0.574, -0.119, -0.226, -0.473 and -0.455, respectively) and positively correlated with HDL-C (r = 0.368), whereas sdLDL-C was positively correlated with age, TC, TG, LDL-C (r = 0.633, 0.485, 0.561 and 0.705, respectively) and negatively with HDL-C (r = -0.235). Stepwise multiple regression analysis demonstrated HDL-C and menopausal status as the best determinant for PON1 (R(2) = 0.320, p < 0.05) and menopausal status, LDL-C, TG, and TC were the best determinants for sdLDL-C (R(2) = 0.606, p < 0.05).

CONCLUSION

The results of the present study suggest quality, i.e., sdLDL-C, is more important than only LDL-C levels. Similarly, decrease in PON1 and increase in sdLDL-C go hand in hand. This shows that antioxidant capacity is compromised with a qualitative downfall in lipoproteins in postmenopausal women.