Behavior of Plasma Renin Activity in Patients with Chronic Renal Failure treated by Hemodialysis

Abstract

The present study was undertaken in an effort to elucidate the complex relationship between hyperension, renin, sodium and water balance in patients with chronic renal failure treated by hemodralysis. Thirty-nine patients were studied. They were divided into 3 groups according to the duration of dialysis: group I, 18 patients dialysed for 1-9 months; group II, 12 patients for 10-19 months; and group III, 9 patients for more than 20 months. Plasma renin activity (PRA) in peripheral vein blood was estimated radioimmunologically. The dialysis was carried out in a closed system against 50 L dialysate fluid, so the amounts of water, sodium, and other solutes dialysed-out from the body were easily measured. There proved a significant correlation between PRA before dialysis (pre-dialysis PRA) and the removed sodium/water ratio (removed sodium/removed water) obtained by the preceding dialysis in patient with long-term hemadialysis (group III). There was no correlation between PRA after dialysis (post-dialysis PRA) and removed sodium, or removed water; or the removed sodium/water ratio in all 3 groups. PRA ratio (pre-dialysis PRA/post-dialysis PRA) was correlated to the removed sodium/water retio in all cases, but the correlation was closer in the long-term dialysis patients (group III). The increase in PRA in relation to the removed sodium/water ratio tended to be high in the initial stage (group I), and become stabilized at a low value as the duration of treatment was prolonged (group III). From these results, it seems that the most important f acor regulating renin release is the removed sodium/water ratio.