Renal vein renin: value and limitations in the prediction of operative results.

Renal vein renin determinations, in contrast to isolated peripheral venous renin determinations, provide great help in the selection of patients who can benefit from an operation for renal hypertension. Patients with essential hypertension usually have renal vein renin ratios, larger/smaller, close to unity, but the available cumulative data show that, statistically, ratios as large as 2.0 may occur in this group (95 per cent confidence limits). In patients with unilateral stenosis of a main renal artery, large renal vein renin ratios (stenotic/normal) have been followed by operative success in more than 90 per cent of patients. However, many operative successes have also been achieved in patients without a large renal vein renin ratio. This may be explained by inaccurate renal vein catheterization, inactive renin secretion, nonsimultaneous sampling, assay variability, and problems related to bilateral or segmental lesions. Recent refinements in the interpretation of renal vein renin data (contralateral suppression, ipsilateral hypersecretion in absolute terms, and a combination analysis scoring system) appear to increase the accuracy of the test. Detailed anatomic information, provided by arteriography, is essential for proper interpretation of renal vein renin data.