Patients with familial hypercholesterolaemia have elevated cholesterol levels due to a genetic defect; patients with common hypercholesterolaemia usually have a metabolic disorder due to an acquired unhealthy lifestyle.
Patients with common hypercholesterolaemia usually develop elevated cholesterol levels in middle age or later; patients with familial hypercholesterolaemia usually have significantly elevated cholesterol levels from birth or adolescence and have blood cholesterol levels that are more than several times the normal value.
Patients with familial hypercholesterolaemia respond significantly less well to lipid-lowering therapy than patients with ordinary hypercholesterolaemia, and it is almost impossible to achieve cholesterol-lowering goals with improved diet and exercise, and often requires a combination of statins and cholesterol absorption inhibitors, or even plasma exchange, to get the lipids up to standard.