Excretory Urogram in Renal Arterial Hypertension

Diagnostic value of captopril test in hypertensive patients with renal artery stenosis

To examine the utility of the single-dose captopril test in detecting renovascular hypertension (RVHT), the authors measured peripheral plasma renin activity (PRA), before and thirty and sixty minutes after an oral dose of captopril (25 mg), in 28 patients with RVHT and 22 patients with high-renin essential hypertension (EHT) without renal artery stenosis who were consuming 8 grams of sodium chloride per day. There was considerable overlap of individual values in basal PRA between the two groups. Sixty minutes after captopril, PRA was higher in RVHT than in EHT patients (74.8 +/- 63.9 versus 15.1 +/- 11.9 ng/mL/hr, P < 0.01). With the cutoff point set at 16 ng/mL/hr, RVHT was detected with a sensitivity of 96% and a specificity of 77%. The discriminating power was also superior to that based on blood pressure response to angiotensin II analogue under sodium depletion, rapid-sequence intravenous pyelography, or renography. These results show that captopril-stimulated peripheral PRA is an adequate screening tool for detecting RVHT in a population with high-renin hypertension.

Indication for intervention in patients with renovascular hypertension

It is now possible to accurately identify patients with renovascular hypertension who need renal angioplasty or revascularization. Evaluation does not require hospitalization and begins with the determination of an ambulatory plasma renin activity (PRA) indexed against sodium excretion and a captopril test. Subsequently differential renal vein renins with matching inferior vena caval (IVC) renins are measured often with converting enzyme inhibition. Identifying criteria are as follows: (1) high PRA indexed against sodium excretion, (2) hypersecretion of renin following captopril administration, (3) absence of renin secretion from the contralateral kidney, and (4) an ipsilateral renal vein renin increment at least 50% greater than the matching IVC renin. Patients who meet the criteria are admitted for percutaneous transluminal renal angioplasty.

Washout urography in the diagnosis of renal hypertension

Washout urography was used as a screening test for 100 hypertensive patients. Eleven patients had renal hypertension. These were 4 cases of unilateral renal artery stenosis, 6 cases of unilateral pyelonephritis and one case of bilateral pyelonephritis with atherosclerosis of the right renal artery. The increase in size of the affected kidneys after Lasix injection was much restricted relatvie to the normal contralateral kidneys. The test proved valuable for screening cases of renovascular hypertension and unilateral pyelonephritis.