title: Blood viscosity and peripheral vascular resistance in patients with untreated essential hypertension.
abstract: OBJECTIVE
  The viscosity of blood is increased in patients with essential hypertension. The aim of the present study was to investigate the importance of the different variables of blood rheology to total peripheral resistance, and to elucidate whether inappropriate regulation of the formation of erythropoietin could be important.
  
  
  METHODS
  Nineteen consecutive patients with untreated essential hypertension were examined and compared with a group of matched healthy volunteers.
  
  
  METHODS
  The haemorheologic variables were assessed by rotational viscometry and the haemodynamic variables by bioimpedance cardiography. The serum concentrations of erythropoietin were determined by radioimmunoassay.
  
  
  RESULTS
  The whole blood viscosity and peripheral resistance index were elevated in the hypertensive group. The two variables were positively correlated with each other (r = 0.68, P = 0.0015). The plasma viscosity and erythrocyte aggregation tendency were increased and the erythrocyte deformability, measured as fluidity, was decreased in the hypertensive patients. In the male subpopulation (n = 12) the aggregation tendency was positively, and the deformability negatively, correlated with body mass index. The serum concentrations of erythropoietin were equal in the two groups.
  
  
  CONCLUSIONS
  The increased total peripheral resistance in patients with essential hypertension may in part be explained by an increased blood viscosity, but the possibility of an opposite cause-effect relationship must also be taken into consideration. The haemorheological abnormalities observed in the present patients cannot be explained by high serum levels of erythropoietin.
authors.affiliation: Department of Internal Medicine, University Hospital, Uppsala, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Linde
authors.forename: B
authors.initials: B
authors.lastname: Sandhagen
authors.forename: A
authors.initials: A
authors.lastname: Hägg
authors.forename: C
authors.initials: C
authors.lastname: Mörlin
authors.forename: B
authors.initials: B
authors.lastname: Wikström
authors.forename: B G
authors.initials: BG
authors.lastname: Danielson
mesh_terms: D000328:Adult; D001809:Blood Viscosity; D005260:Female; D006439:Hemodynamics; D018056:Hemorheology; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D014655:Vascular Resistance