RENOVASCULAR HYPERTENSION WITH LOW-TO-NORMAL PLASMA-RENIN - CLINICAL AND ANGIOGRAPHIC FEATURES

1. Low-to-normal renin renovascular hypertension (RVH) and the accurac y of renal vein renin ratios were investigated in 129 consecutive pati ents referred for suspected RVH, Forty-nine had essential hypertension , 24 unilateral renoparenchymal hypertension and 56 renal artery obstr uction, Of the latter, 86% were diagnosed retrospectively as RVH, base d on fall in blood pressure with correction of renal ischaemia, We mea sured baseline, captopril-stimulated and renal vein plasma renin activ ity (PRA) levels, as well as several other parameters. 2. PRA was low- to-normal in 37% of the RVH patients [low-to-normal renin (LNR-) RVH g roup] and elevated in the remaining 63% [high-renin (HR-) RVH group], In the LNR-RVH group, low-to-normal renin levels, by immunoreactive ac tive renin and plasma renin concentration measurements, and a blunted response of PRA to captopril, were seen, As compared with HR-RVH, LNR- RVH patients had a longer duration of hypertension (P < 0.05), higher serum K+ (P = 0.04) and lower diastolic blood pressure (P = 0.02), How ever, they did not differ for the other variables, including the fall in blood pressure after correction of renal ischaemia, Although the nu mber of bilateral stenoses was similar in the two groups, no patient i n the LNR-RVH group had total renal artery occlusion compared with 53% in the HR-RVH group (P = 0.00015), The accuracy of renal vein renin i ndices were high enough to justify their use only in the patients with total occlusion of a renal artery. 3. Thus LNR-RVH is common in patie nts with long-standing hypertension without a totally occluded renal a rtery, Since the sensitivity of renin measurements is low, cure of hyp ertension would be precluded for more than one third of RVH patients, if these tests were a prerequisite for identifying RVH.