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
S. Nakajima et al., 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, PLATELETS, 11(8), 2000, pp. 459-466
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.