Renal artery stenosis may cause no signs or symptoms until the condition reaches an advanced state. Most people with renal artery stenosis have no signs and symptoms. The condition is sometimes discovered incidentally during testing for some other reason. Your doctor may also suspect a problem if you have:

• High blood pressure that begins suddenly or worsens without explanation
• High blood pressure that begins before age 30 or after age 50

As renal artery stenosis progresses, other signs and symptoms may include:

• High blood pressure that's difficult to treat
• A whooshing sound as blood flows through a narrowed vessel (bruit), which your doctor hears through a stethoscope placed over your kidneys
• Elevated protein levels in the urine or other signs of abnormal kidney function
• Worsening kidney function during treatment for high blood pressure
• Fluid overload and swelling in your body's tissues
• Treatment-resistant heart failure

The two main causes of renal artery stenosis include:

• Atherosclerosis of the renal arteries. Atherosclerosis is the buildup of fats, cholesterol and other substances (plaques) in and on your artery walls. As the deposits get larger, they can harden, reduce blood flow and cause scarring of the kidney. Eventually, narrowing of the artery can result. Most cases of renal artery stenosis occur because of atherosclerosis.
• Fibromuscular dysplasia. In fibromuscular dysplasia, the muscle in the artery wall grows abnormally. The renal artery can have narrow sections alternating with wider sections, giving a beadlike appearance in images of the artery.

The renal artery can narrow so much that the kidney doesn't receive an adequate supply of blood and can become damaged. This can happen in one or both kidneys. Experts don't know what causes fibromuscular dysplasia, but the condition is more common in women and may be something that's present at birth (congenital).

Atherosclerosis and fibromuscular dysplasia can affect other arteries in your body as well as your kidney (renal) arteries and cause complications.

Rarely, renal artery stenosis results from other conditions such as inflammation of the blood vessels (vasculitis); a nervous system disorder that causes tumors to develop on nerve tissue (neurofibromatosis); or a growth that develops in your abdomen and presses on your kidneys' arteries (extrinsic compression).

Most cases of renal artery stenosis result from atherosclerosis. Risk factors for atherosclerosis of the renal arteries are the same as for atherosclerosis anywhere else in your body and include:

• Aging
• High blood pressure
• High cholesterol
• Diabetes
• Obesity
• Smoking and other tobacco use
• A family history of early heart disease
• Lack of exercise

Possible complications of renal artery stenosis include:

• High blood pressure (renovascular hypertension)
• Kidney failure, requiring treatment with dialysis or a kidney transplant
• Fluid retention (edema) in your legs, causing swollen ankles or feet
• Shortness of breath due to a sudden buildup of fluid in the lungs (flash pulmonary edema)