Increased levels of small dense low-density lipoprotein cholesterol associated with hemorheological abnormalities in untreated, early-stage essential hypertensives.

Among subfractions of low-density lipoprotein cholesterol (LDL-C), small dense LDL-C (SdLDL-C) has been highlighted as the most atherogenic lipoprotein cholesterol. The present study aimed to compare the relationship of SdLDL-C with blood viscosity, a surrogate marker for cardiovascular disease, with that of other lipid fractions with blood viscosity in essential hypertensives (EHTs). In 128 untreated, early-stage EHTs, blood viscosity was measured with a falling-ball microviscometer, and serum levels of lipid fractions were determined. Blood and plasma viscosity was significantly higher in 49 patients with dyslipidemia (fasting serum level of LDL-C > 140 mg dl(-1), triglyceride > 150 mg dl(-1) or high-density lipoprotein cholesterol (HDL-C) < 40 mg dl(-1)) compared with 79 patients without dyslipidemia, although hematocrit and RBC rigidity index 'k' did not differ between the two groups. Together, SdLDL-C, LDL-C, triglyceride and large LDL-C were positively correlated with blood viscosity, but for HDL-C, the correlation was negative. After adjusting for non-lipid variables that correlated with blood viscosity (that is, the age, body mass index, resting diastolic blood pressure, sex, hematocrit, plasma viscosity and homeostasis model of assessment of insulin resistance), SdLDL-C was most strongly associated with blood viscosity among the lipid fractions. These data suggest that SdLDL-C could strongly increase blood viscosity in EHTs.