Hyperalphalipoproteinemia in hypercholesterolemic adults and children.

This report was designed to describe and characterize the proportion of of hypercholesterolemic children and adults in the Lipid Research Clinics collaborative prevalence study whose elevated total plasma cholesterol levels were accounted for by elevated high density lipoprotein cholesterol (C-HDL), not by elevated levels of low density lipoprotein cholesterol (C-LDL). In randomly recalled 6-19 year old children having age-, race-, an sex-specific plasma cholesterol levels greater than or equal to 95th percentile levels, 22% of white males, 22% of white females, and 44% of black males had C-HDL, but not C-LDL greater than or equal to age-, sex-, and race-specific 95th percentile levels. In contrast, for adults (ages 20-79 years), 3% of white males, 10% of white females, 17% of black males, and 25% of black females had predominant hyperalphalipoproteinemia which accounted for their hypercholesterolemia. In participants defined as hypercholesterolemic on the basis of two examinations it was observed that the majority of children and adults were in the C-LDL elevated and C-HDL not elevated category. Hypercholesterolemic adults were not as likely as the hypercholesterolemic children to be in the C-HDL elevated and C-LDL not elevated category. For both children and adults, blacks were more likely to have predominant hyperalphalipoproteinemia accounting for their elevated total plasma cholesterol levels than were whites. For hyperalphalipoproteinemic, hypercholesterolemic children and adults, the mean ratio of C-LDL to C-HDL ranged from 1.3 to 1.4 (in children) and 1.4 to 2.1 (in adults), levels well below the overall mean ratio for the entire Lipid Research Clinics random recall group of 2.7 for children and 4.2 for adults. An understanding of the multiple etiologies of hyperalphalipoproteinemic-hypercholesterolemics may be useful in considering programs designed to elevate C-HDL over time, with an aim at reducing CHD risk.