Hyperviscosity and thrombotic changes in idiopathic and secondary Raynaud's syndrome.

Whole-blood viscosity (measured at 128, 23 and 0.2 s-(1) was significantly increased in 29 females with Raynaud's syndrome, 13 males with vibration-induced Raynaud's syndrome, and 18 males with calf claudication secondary to atherosclerosis, as compared with 50 healthy controls matched for sex, age and smoking habit. Viscosity was higher at low temperature (27 and 22 degrees C) in all three types of vascular disease and, despite symptoms of cold hypersensitivity, patients with Raynaud's syndrome did not show selective hypersensitivity at low temperature. Patients with vascular disease, irrespective of aetiology, also showed an increase in the acute-phase reactants haptoglobin, fibrinogen, and factor VIII antigen, together with reduced fibrinolytic activity and minor activation of platelets. These alterations in viscosity and haemostatic factors in vascular disease are probably related to the degree, rather than the aetiology, of endothelial damage and their cumulative effect may contribute to local stasis and thrombosis, particularly in cold extremities.