Renal vein renin activity in primary hypertension: variability and influence of contrast material.

Despite recognized limitations, the renal vein renin ratio (RVRR) remains the most commonly used index of surgical curability in hypertensive patients with renal artery stenosis. It is generally held that a ratio exceeding 1.5 forecasts a favorable response to surgery. Measurement of this ratio in 40 patients with essential hypertension (no arteriographically demonstrated stenosis) showed 8 (20%) with RVRR over 1.5, confirming an overlap of this ratio between patients with essential and renovascular hypertension. Intra-arterial injection of contrast material influenced renal vein renin activity (RVRA) in some individuals, but we were unable to demonstrate significant alterations in the group as a whole. Since the influence of intra-arterial contrast material on RVRA is variable and unpredictable, it appears unwise to collect renal venous blood for renin measurements soon after angiography.