INCREASED PLATELET VOLUME AND PLATELET MASS IN PATIENTS WITH ATHEROSCLEROTIC RENAL-ARTERY STENOSIS

1. Platelet volume was measured in citrated blood in two groups of patients at risk of having atherosclerotic renal artery stenosis, namely (i) 30 patients with severe hypertension, and (ii) 44 patients with peripheral vascular disease. 2. Platelet volume was increased in patients with hypertension who had atherosclerotic renal artery stenosis diagnosed by angiography: no renal artery stenosis, median 7.2 (interquartile range 0.5) x 10(-15)/l; renal artery stenosis 7.8 (0.8) x 10(-15)/l; platelet mass also increased with increasing severity of renal artery stenosis. Platelet volume correlated with severity of renal artery stenosis (r(s) = 0.391, 2p = 0.033, n=30). Similarly, platelet volume correlated with severity of renal artery stenosis in patients with peripheral vascular disease (r(s)=0.319, 2p=0.035, n=44). Serum immunoreactive platelet-derived growth factor (predominantly released from platelets) and plasma immunoreactive interleukin-6 (a cytokine which has been postulated to regulate platelet volume) concentrations were not different between hypertensive patients with and without renal artery stenosis. 3. Since large platelets are hyperactive, increased platelet volume may contribute to the development of atherosclerotic renal artery stenosis. However, the present data do not lend support to the hypothesis that platelet-derived growth factor is central to renal artery atherogenesis. Interleukin-6 does not appear to regulate platelet volume.