Release of renal renin in patients under long-term dailysis treatment.

Abstract

Plasma renin activity (PRA) was studied in 61 patients under long-term dialysis treatment. They were divided into 3 groups, low (0.1-5.0 ng/ml), normal (5.1-30.0 ng/ml) and high renin groups (more than 30.1 ng/ml) according to the levels of PRA. The difference in clinical features in the 3 groups and the factors influencing the secretion of renin were investigated. With regard to the pre-dialysis PRA (resting PRA), low renin levels were found in 13.1% of patients, normal in 65.5% and high in 21.4%. The pre-dialysis PRA (resting PRA) was significantly correlated with .DELTA.PRA/removed-Na, but not with the removed Na or removed water by the preceding dialysis. Severe retinal changes were observed in patients with high resting PRA values. Fundoscopic findings were mild in patients with low resting PRA values. Elevated resting PRA values were obtained in younger subjects under 29 yr of age, while the PRA levels were very low in patients of advanced ages (over 60 yr). The latter showed low levels of .DELTA.PRA/removed-Na. Though the ratios of .DELTA.PRA/removed-Na were very low in patients under hemodialysis for over 3 yr, the resting PRA levels did not decrease with the duration of dialysis treatment, because renin secretion was stimulated strongly by the excessive removal of Na and water in these later periods of hemodialysis. With regard to the post-dialysis PRA, low renin levels were found in 6.8% of patients, normal in 55.9% and high in 37.3%. Post-dialysis PRA were significantly correlated with the pre-dialysis PRA and the .DELTA.PRA/removed-Na. High PRA may be a risk factor producing the hypertensive complications and .DELTA.PRA/removed-Na may be a most important factor controlling the levels of PRA (pre-dialysis PRA and post-dialysis PRA). Age, removed Na, removed water and the duration of dialysis also might be concerned with the secretion of renin.