Divergent Levels of High Density Lipoprotein Cholesterol and Apolipoprotein A-l in Children

Clinical studies Indicate that levels of apolipoprotein A-l (apo A-l), the major protein moiety of the high density lipoprotein (HDL) particle, may provide more Information concerning the risk of future cardiovascular disease than do levels of HDL cholesterol (HDL-C). Therefore, the relationship of HDL-C to apo A-l levels was examined In a blraclal sample of 2849 5to 17-year-olds. The mean HDL-C to apo A-l ratio, a measure of HDL composition, was 0.42. However, marked Interindlvldual variation was found: HDL-C/apo A-l levels varied from 0.27 (10th percent!le) to 0.57 (90th percentlle). Furthermore, only 26% of the variation In HDL-C levels was explained by concomitant variation In apo A-l. Increasing levels of trlglycerlde (and very low density lipoprotein cholesterol) were related to decreases In both the HDL-C/apo A-l ratio and the magnitude of the correlation between HDL-C and apo AH. Low density lipoprotein cholesterol, race, and age were also related to the HDL-C/apo A-l ratio, but Influenced HDL composition less strongly than did trlglycerlde levels. These observations may be explained by the bidirectional transfer of cholesteryl esters and trlglycerldes between HDL and triglyceride-rlch llpoprotelns. The current study documents the Influence of trlglyceride levels on HDL composition in a general population of children and adolescents, and emphasizes the Interrelationships between the various llpld and lipoprotein fractions. (Arteriosclerosis 7:347-353, July/August 1987)