Abnormal blood rheology in progressive renal failure: a factor in non-immune glomerular injury?

Chronic renal insufficiency progresses by a final common pathway of glomerular damage characterised by microvascular injury and glomerulosclerosis. In order to investigate the possible role of blood rheology in this process, rheological indices were compared between healthy controls and a group of patients with progressive renal failure due to renal diseases that were not considered to be immunologically mediated. Plasma viscosity was significantly increased in the renal insufficiency group (P less than 0.005), and correlated with raised plasma concentrations of fibrinogen (r = 0.63; P less than 0.005). Whole-blood viscosity corrected to a standard haematocrit of 0.45 was also raised. A weak but significant correlation was seen between plasma viscosity and 24-h urinary protein excretion (r = 0.50; P less than 0.005). Our data show that in chronic renal insufficiency, rheology is abnormal. Proteinuria correlates with plasma viscosity, which is consistent with the hypothesis that raised plasma viscosity leads to an increase in glomerular capillary pressure and thence glomerular permeability. Correction of rheological abnormalities might help to preserve kidney function and reduce proteinuria in these patients.