Renal artery stenosis is caused when atheroembolic renal disease results in narrowing of the renal artery. Fibromuscular disease, a condition more common in young women in which fibrous tissue grows in the wall of the renal artery and narrows it, is a second cause. It may also be caused when scar tissue forms in the renal artery after acute arterial obstruction or traumatic injury to the kidney.

Renal artery stenosis often causes hypertension with no other signs of its presence, and it is usually discovered in investigation for the cause of hypertension that is difficult to control. Renal artery stenosis is, in fact, among the most common causes of secondary hypertension (see hypertension). The disorder may also be discovered when a bruit (loud whooshing sound) over the kidney is noted on a routine examination, or an examination of the abdomen for other disorders.

In the elderly, renal artery stenosis is most commonly associated with atherosclerotic disorders, including atherosclerotic heart disease. Atherosclerotic plaque deposits within the renal artery and causes it to become stenosed (narrowed).

Fibromuscular dysplasia is a congenital disorder involving thickening of the arterial wall and is a cause of renal artery stenosis in younger adults, particularly women 20 to 40 years old.

Renal artery stenosis may cause chronic renal failure if it affects both renal arteries or if the hypertension associated with this condition is prolonged or severe.

• A radionuclide renogram may indicate a decreased blood flow. The value of radionuclide scanning is increased if the test is done twice: once after a dose of captopril and once without the captopril.
• A kidney X-ray, kidney CT scan, or kidney ultrasound may indicate a decreased size of the kidney, and/or a decreased arterial flow secondary to narrowing of the artery.
• Renal arteriography shows the exact location of the stenosed area.

• Urine specific gravity
• Urine concentration test
• Renal perfusion scintiscan

The treatment varies depending on the extent and severity of the symptoms. The second kidney may take over filtering and urine production for the body if the stenosis results in failure of that kidney. Surgical repair of the stenosed area may be possible.

A balloon angioplasty (a radiographic procedure during which a balloon-tipped catheter is threaded through the artery) or stent placement across the stenosis may be an alternative method of opening the stenosed area instead of surgery.

Antihypertensive medications may be needed to control high blood pressure.

• Hypertension
• Malignant hypertension
• Chronic renal failure