Serum lipoprotein concentration and composition in healthy 50-year-old men.

The classification of hyperlipoproteinaemias (HLP) is based on arbitrary limits between "normolipidaemia" and "hyperlipidaemia". 92 randomly selected healthy 50-year-old men were studied regarding serum lipoprotein (LP) lipid composition to define limits for "normality". Cholesterol and triglyceride concentrations were determined and the individual ratios between cholesterol and triglycerides were calculated in the ultracentrifugally isolated LP density classes. A significant linear correlation between cholesterol and triglyceride concentrations was found in the very low density lipoproteins (VLDL) and low density lipoproteins (LDL) but not in the high density lipoproteins (HDL). When different percentile limits for LDL cholesterol and VLDL triglycerides were used as cut-off points for "normality" not only the absolute prevalence but also the relative frequency of different types of HLP was influenced. 26 overweight men studied separately showed significantly increased VLDL cholesterol and triglyceride levels with maintenance of the normal ratio cholesterol/triglycerides of this LP class compared with non-obese subjects. Three different kinds of "extra bands" were occasionally seen on agarose electrophoresis: a "double pre-beta" band in whole serum (3%), a "sinking pre-beta" band with density greater than 1.006 (17%) and a "late pre-beta" band in VLDL (22%). While "sinking pre-beta" is identical with Lp (a) LP the "late pre-beta" band probably represents a certain accumulation of "intermediary particles".