Renal Vein Renin Sampling

Renal vein renin sampling can be performed in the evaluation of renovascular hypertension in children. Blood samples are taken from the infrarenal inferior vena cava, the main renal veins, and from upper, middle, and lower renal vein tributaries, taking care to avoid tributaries of the renal veins to capsular or lumbar veins or the left gonadal vein. Renal vein renin sampling can help guide treatment to the side that has clinically important lesions and selective sampling from segmental veins can provide more precise localization of the hypertensive focus.

A ratio of > 1.5 between the two main renal veins is considered significant, with the side with the higher renin being abnormal. A ratio of greater than 1.3 between the suspected normal kidney and the infrarenal inferior vena cava is considered supportive. A positive result has been suggested as a good predictor of favorable outcome following angioplasty or surgery.

Renal vein renin sampling a more useful diagnostic tool in children than in adults, because renal artery abnormalities in children are usually bilateral and involve small arterial branches.

References

• Dillon MJ. The diagnosis of renovascular disease. Pediatr Nephrol. 1997 Jun;11(3):366-72.
• McLaren CA, Roebuck DJ. Interventional radiology for renovascular hypertension in children. Tech Vasc Interv Radiol. 2003 Dec;6(4):150-7. Review.