Elevated Plasma Renin Activity Associated with Renal Dysfunction

Elevated plasma renin activity (PRA) has been documented in patients with established acute renal failure. To study the association of PRA and renal dysfunction, 53 patients who were at risk of developing acute renal failure had serial measurements of PRA, renal function, and urinary beta 2-microglobulin. Those entered for study had pneumonia, septicaemia, volume loss with hypotension, or major surgical procedures with complications. Patients were divided into groups of abnormal or normal renal function. Abnormal renal function was defined by an elevated plasma urea and/or creatinine level with a submaximal urine urea to plasma urea ratio. The mean values of PRA for the abnormal and normal renal function groups, respectively, were 29 and 5.2 ng/ml/h (p less than 0.0001) and for beta 2-microglobulin 16.2 and 6.4 micrograms/l X 10(3) (p less than 0.0005). A linear regression of the logs of PRA to beta 2-microglobulin for the total group of patients gave an r value of 0.526 (p less than 0.001). These data show an association of PRA to renal dysfunction and tubular injury/dysfunction in the prerenal phase of renal failure, suggesting an effect of the renin-angiotensin system at this phase. It is not possible, however, to conclude from our study that the renin-angiotensin system has a direct role in the development of established acute tubular necrosis, since only 3 patients fell within this category.