PLASMA-RENIN ACTIVITY AS A MARKER OF RENOVASCULAR INJURY IN PATIENTS WITH RHEUMATOID-ARTHRITIS

Objectives. To assess whether plasma renin activity (PRA) inpatients w ith rheumatoid arthritis (RA) and evidence of renal involvement (micro hematuria) can serve as potential marker of renovascular injury. Metho ds. PRA was measured at rest and following exercise. All nonsteroidal antiinflammatory drugs or other medications that might affect renin re lease were stopped at least ten days prior to PRA measurments. PRA was correlated with the number of dysmorphic erythrocytes present in the urine sediment as indicators of glomerular capillary injury (microhema turia). Results. All patients with RA had a higher mean PRA than contr ols. Moreover, all patients with RA in whom microhematuria was present had a higher PRA than those without microhematuria. Simple and multip le regression analysis revealed a significant correlation between: a) PRA and rheumatoid factor levels; b) rheumatoid factor levels and the number of erythrocytes in the urine sediment; and c) PRA levels and th e number of erythrocytes in the urine sediment. Conclusions. The obser vations indicate that increased PRA may occur in normotensive patients with RA and no clinical or biochemical evidence of renal involvement This may reflect activation of the renin-angiotensin system. The posit ive correlation between enhanced PRA, rheumatoid factor levels and mic rohematuria in RA patients may indicate inflammatory injury of the glo merular microvasculature involving the juxtaglomerular apparatus.