Hyperlipidaemia, smoking and hypertension. The place of the hyperlipidaemias.

Of the primary hyperlipidaemias, familial hypercholesterolaemia (hyerbetalipoproteinaemia, type II) is always expressed in childhood and carries a high risk for the early development of coronary heart disease. The diagnosis can be established with a high degree of certainty by estimating the serum cholesterol concentration in selected children in whom the genetic risk is known to be great, e.g. if a parent or other first-degree relative is known to have the disease, or if a parent has had an attack of ischaemic heart disease at a young age. Screening of the general population in order to detect this disorder is not advocated. Treatment by either diet or drugs will lower serum cholesterol but long-term compliance is poor and the effect of treatment on the atherosclerotic process has not been evaluated. Follow-up studies must be maintained. Familial hypertriglyceridaemic states are rarely fully expressed during childhood, and screening for them at this age is not practicable. Control of co-existent obesity and dietary treatment are usually successful in lowering serum lipids but long-term results have not yet been evaluated. In a childhood population, single estimations of serum cholesterol or triglyceride should be interpreted with caution. Percentile rank correlations for serum cholesterol are of the order of 0·61 and for triglyceride of 0·31. Prediction of adult values cannot therefore be assured in childhood and the place of hyperlipidaemia in the childhood population as a risk factor for coronary heart disease in adult life is not established. Thus population screening of serum lipids in children cannot be justified. Evidence that a change in the diet of children which would be expected to lower serum lipids will also delay the development of atherosclerosis in general and coronary heart disease in particular is lacking. Nevertheless the dietary changes which have been recommended for adults can safely be followed by children, and changes in eating habits are perhaps more likely to succeed if promoted on a family basis rather than for individual sections of the population.