INCREASED BLOOD VISCOSITY AND FIBRINOLYTIC INHIBITOR IN TYPE II HYPERLIPOPROTEINAEMIA

Abstract

Blood rheology and several haemostatic factors were studied in patients with type II hyperlipoproteinaemia (HLP) and matched controls. HLP patients had increased blood viscosity (p<0·01), the mean level being 18% higher at a low shear-rate (0·94 s -1) and 13% higher at a high shear-rate (94 s -1). The increased viscosity was due partly to a raised haematocrit (p<0·05), and partly to increased plasma viscosity (p<0·01) associated with increased plasma fibrinogen (p<0·02). Red cell deformability was normal, and viscosity was unrelated to either lipid or lipoprotein concentrations. Levels of the major fibrinolytic inhibitor, α 2-antiplasmin, measured by both functional and immunological techniques were higher in HLP patients (mean increase 30-32%). Plasminogen activator levels were normal in HLP patients and the ratio of fibrinolytic inhibitor to activator was therefore increased. Plasminogen concentrations were also increased. Levels of factor VIII activity and antigen, antithrombin III and anti-factor Xa activity, α 2-macroglobulin, platelet count, and platelet aggregation by adenosine diphosphate and adrenaline did not differ significantly in HLP patients and controls. These results suggest that the premature arterial disease associated with HLP may be related to increased blood viscosity, which reduces arterial blood flow, and increased α 2-antiplasmin, the major inhibitor of fibrinolysis.