A global platelet test of thrombosis and thrombolysis detects a prothrombotic state in some patients with non-insulin dependent diabetes and in some patients with stroke

Platelet aggregation and spontaneous thrombolytic activity were assessed in patients with non-insulin dependent diabetes and stroke using a shear-indu ced and agonist-induced platelet aggregation test. The Thrombotic Status An alyser (TSA), induces platelet-rich thrombus formation solely by shear forc es, while whole blood platelet aggregometry measures platelet reactivity to different agonists. These tests were employed in the present study because in earlier studies they both demonstrated that platelet aggregability in h ealthy volunteers was unchanged with age. On the other hand, it is known th at thrombolytic activity decreases with age in males, but not in females. I n diabetic patients shear-induced platelet aggregability varied according t o the stage of nephropathy but platelet aggregation to collagen was suppres sed at all stages. Platelet reaction to shear stress was enhanced in stroke patients with haemorrhagic episodes but not in patients with lacunar infar ction. In contrast, platelet reactivity to collagen was suppressed and chan ges in ADP-induced platelet aggregability were inconsistent. Suppressed thr ombolysis was observed only in diabetes with minor renal defect. Fibrinogen was increased in diabetes with stage III and IV nephropathy. Fibrinopeptid e A (FPA) and D-dimer were increased in stroke. Thus, the observed increase in fibrinogen, FPA and D-dimer is inconsistent with changes in platelet ag gregability. Our present findings suggest that a shear-induced platelet agg regation test is superior to other tests such as agonist-induced platelet a ggregation and thrombotic markers such as fibrinogen, FPA and D-dimer in de tecting a prothrombotic state. It is concluded that elderly males may have a prothrombotic state not because of platelet hyper-aggregability but becau se of suppressed thrombolytic activity. On the other hand, a prothrombotic state in patients with non-insulin dependent diabetes and after stroke may be due to changes in age-independent platelet aggregability.