[Studies on the differential determination of renin activity in renal venous blood in renal artery stenosis].

Plasma renin activity (PRA) was determined in both renal veins of 37 patients with angiographically proven renal artery stenosis. Renal venous PRA was determined in 17 patients without furosemide stimulation and in 20 patients before and 15 and 30 min after intravenous injection of 40 mg furosemide. 21 of 37 patients showed abnormally high peripheral PRA. In the 17 patients in whom renal venous PRA was measured without stimulation, 11 showed a PRA ratio (PRA stenotic side/PRA unaffected side) greater than or equal to 1.5. The 20 patients in whom stimulation with furosemide was performed were divided into 2 groups each containing 10 patients: The first group was characterized by an increase in PRA ratio after furosemide stimulation, while in the second group this PRA ratio decreased. In the first group mean duration of hypertension was 4.5 years compared to 7.5 years in the second group. In 17 of 37 patients renal artery stenosis was corrected by surgery. After operation 12 patients became normotensive and in 2 patients hypertension improved. There was no effect of renovascular surgery on blood pressure in only 3 patients. None of these patients showed an increasing ratio in response to furosemide. Our results suggest that the validity of renal venous PRA measurements is enhanced when the procedure is performed before and after administration of furosemide.