What is the role of the renal vein renin ratio in the workup of renovascular hypertension (RVHT)?

Updated: Dec 01, 2020
  • Author: Rebecca J Schmidt, DO, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Renal vein renin measurements compare renin release from the 2 kidneys and are used to predict the potential success of surgical revascularization. Renin secretion is increased in the ischemic kidney but is suppressed in the contralateral kidney, as evidenced by the similar levels of renin measured in the renal artery (infrarenal inferior vena cava) and the renal vein.

The ratio of the measurement from the ischemic kidney to the measurement from the contralateral kidney is the renal vein renin ratio. A ratio higher than 1.5 constitutes a positive test result and is suggestive of functionally important renovascular disease. Volume depletion exaggerates reduced renal perfusion and may increase the renal vein renin ratio in asymmetric disease.

Fewer than 10% of healthy patients have a renal vein renin ratio higher than 1.5, and less than 20% have a ratio lower than 1.1. It has been suggested that the accuracy of these measurements can be enhanced by prior administration of an angiotensin-converting enzyme (ACE) inhibitor, which will increase renin secretion on the affected side.

False-negative and false-positive results are common. [34] Although more than 90% of patients with unilateral RAS and lateralizing renin values respond positively to angioplasty or surgery, about 50% of those with nonlateralizing findings also benefit from correction of the stenosis. [10]

As a result, most physicians rely on the clinical index of suspicion rather than on renal vein renin measurements to estimate the physiologic significance of a stenotic lesion. An exception may occur in patients with bilateral RAS, in whom renal vein renin measurements can be used to determine the side that most contributes to the hypertension. [10]


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