Renal artery stenosis is a narrowing or blockage of the artery that supplies blood to the kidney. It is caused by atherosclerosis, fibromuscular dysplasia of the renal artery wall, or scar formation in the artery. (See also atheroembolic renal disease.)

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 (high blood pressure) 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 (caused by another condition) hypertension. The disorder may also be discovered when a bruit (loud whooshing sound) over the kidney is noted on examination with a stethoscope (auscultation).

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 - 40 years old.

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

There are usually no symptoms.

The blood pressure may be high, and there may be a history of high blood pressure that doesn't respond to medication or is difficult to control. A bruit may be heard on examination with a stethoscope (auscultation) over the kidney.

• A radionuclide renogram may show 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.
• An MRI, kidney CT scan, or kidney ultrasound may indicate a decreased size of the kidney, and/or a decrease in blood flow through the artery because the artery has become narrow.
• Renal arteriography shows the exact location of the stenosed (blocked) area.

This disease may also alter the results of the following tests:

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