Plasma renin activity in patients with renovascular hypertension

Plasma renin activity (PRA) in peripheral and renal vein blood was determined in 25 patients with renovascular hypertension. Significant elevation of resting peripheral vein PRA was observed in only 9 (36%) of them. 11 (61%) out of 18 patients whose conditions were improved by surgery had shown normal levels of resting peripheral vein PRA preoperatively. Provocation test for renin secretion was done in 20 patients. 10 patients showed a hyper-response. 7 out of 15 patients who benefited from surgery had shown no response in PRA on the stimulation. Renal vein PRA was determined in 23 patients. In 16 significantly higher renal vein PRA was found on the affected side. However, measurement of renal vein PRA failed to predict the surgical results in one-third of the patients. Postoperative PRA and blood pressure were followed serially in 10 patients. PRA became normal within 3 days postoperatively in 9 patients. While the normalization of blood pressure following operation was more rapid in 3 revascularized patients than in 7 nephrectomized, the normalization of PRA was quicker in the latter patients than in the former. These data indicate that measurement of PRA in peripheral and renal vein is not an infallible mean to determine the functional significance of renal arterial lesions.