Raised lipoprotein(a) in hypercholesterolaemic black students compared to age-matched whites in North and South Carolina

Abstract

Background: North and South Carolina are the states with the highest coronary death rates and also belong to the Stroke Belt of the US. From a Reflotron cholesterol screening in North and South Carolina schools, students with cholesterol levels > or = 4.66 mmol/l (> or = 180 mg/dl) were tested for high density lipoprotein (HDL), low density lipoprotein (LDL) and lipoprotein(a) (Lp(a)).

Methods: The 923 students aged 12-19 with mild hypercholesterolaemia represented one-third of the high school population, of whom 30% are black. Of the hypercholesterolaemic white students, 96% took the additional tests, of the hypercholesterolaemic black students, 88% responded. Lp(a) levels were determined by electroimmunodiffusion.

Results: Most important was a three-fold elevation of the geometric mean of Lp(a) values among blacks compared to whites: white males 9, white females 10, black males 25, black females 26 mg/dl, respectively, independent of age and sex. Relationships between Lp(a) and four other lipids/lipoproteins were examined and proved non-significant except for total cholesterol and LDL in black males and white females. While 70% of the white students displayed Lp(a) levels < 20 mg/dl, 65-70% of the black students showed Lp(a) levels > 20 mg/dl.

Conclusions: Early identification of high Lp(a) levels may be of importance for two groups, (1) black females who have a 20% higher coronary heart disease mortality rate than white females in spite of significantly higher HDL levels; and (2) for black males and black females who have a prevalence of cerebrovascular disease twice as high as in whites.