VASOACTIVE HORMONES IN UREMIC PATIENTS WITH CHRONIC HYPOTENSION

Background. We evaluated the possible role of an imbalance between vas oconstrictor and vasodilatador hormones in the pathophysiology of chro nic hypotension in uraemia. Methods. Fourteen hypotensive haemodialyse d patients, 14 normotensive haemodialysed patients, and 17 control sub jects were included in this study. Plasma renin activity (PRA) and pla sma levels of catecholamines, angiotensin II (AII), atrial natriuretic peptide (ANP), and arginine vasopressin (AVP) were measured. Results. The mean time on haemodialysis (HD) was longer in hypotensive patient s than in normotensive patients (P<0.01). Catecholamine levels were hi gher in the whole group of HD patients than in controls (P<0.01). Cate cholamine levels were higher in hypotensive patients than in normotens ive patients, but the differences reached significance only for adrena line (P<0.05). PRA. and plasma AII levels were higher in hypotensive p atients than in the other two groups (P<0.05), while no differences we re observed between normotensive patients and controls. Plasma ANP and AVP levels were higher in HD patients than in controls (P<0.01), but there were no differences between hypotensive and normotensive patient s. In HD patients, mean blood pressure inversely correlated with PRA ( r=-0.59, P<0.01) and plasma AII levels (r=-0.80, P<0.01). Conclusions. Our results indicate that in HD patients with chronic hypotension the re is an activation of the sympathetic and the renin-angiotensin syste ms. This activation is probably secondary in an attempt to compensate the vascular resistance to presser stimuli reported in these patients.