Family study of high density lipoprotein cholesterol and the relation to age and sex. The Tromso Heart Study.

A family study of serum high density lipoprotein (HDL) cholesterol and total serum cholesterol concentration has been undertaken, and the relation to age, sex, cigarette smoking, physical activity and familial occurrence of myocardial infarction (MI) was examined. HDL cholesterol was determined in 251 females and 194 males and total serum cholesterol in 677 females and 657 males, all aged 0-49 years. With respect to HDL cholesterol, significant sex differences were observed both in absolute level and in age-related change. A negative correlation between HDL cholesterol and total serum cholesterol was observed in all age groups except females aged 0-19 years, supporting the hypothesis of HDL as a ""clearing'' lipoprotein. HDL cholesterol showed a positive correlation only in pairs of first-degree relatives involving the mother and in sib-sib paris of the same sex. On the other hand, for serum cholesterol a positive correlation was found among all family members, although significantly higher between first-degree relatives than between spouses. No relation was found between cigarette smoking, physical activity of familial occurrence of MI and the HDL cholesterol or total serum cholesterol concentrations. In accordance with the ""HDL hypothesis'', the present finding could partly explain the higher incidence of ischaemic heart disease (IHD) in males than in females, and partly also the high risk which is transmitted from women with IHD to their first-degree relatives.