Renal artery stenosis is the narrowing of one or more arteries that carry blood to your kidneys (renal arteries).
Narrowing of the arteries prevents normal amounts of oxygen-rich blood from reaching your kidneys. Your kidneys need adequate blood flow to help filter waste products and remove excess fluids. Reduced blood flow to your kidneys may injure kidney tissue and increase blood pressure throughout your body.
Renal artery stenosis often doesn't cause any signs or symptoms until it's advanced. The condition may be discovered incidentally during testing for something else. 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 hard to control
- 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
When to seek medical advice
Make an appointment with your doctor if you have any persistent signs or symptoms that worry you.
The two main causes of renal artery stenosis include:
- Buildup on kidney (renal) arteries. Fats, cholesterol and other substances (plaque) can build up in and on your kidney artery walls (atherosclerosis). As these deposits get larger, they can harden, reduce blood flow, cause kidney scarring and eventually narrow the artery. Atherosclerosis occurs in many areas of the body and is the most common cause of renal artery stenosis.
Fibromuscular dysplasia. In fibromuscular dysplasia, the muscle in the artery wall grows abnormally, often from childhood. The renal artery can have narrow sections alternating with wider sections, giving a bead-like appearance in images of the artery.
The renal artery can narrow so much that the kidney doesn't get an adequate supply of blood and can lead to high blood pressure at a young age. 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).
Narrowed kidney arteries and fibromuscular dysplasia can affect other arteries in your body as well as your kidney arteries and cause complications.
Rarely, renal artery stenosis results from other conditions such as inflammation of the blood vessels or a growth that develops in your abdomen and presses on your kidneys' arteries.
Most cases of renal artery stenosis result from narrowed kidney arteries. Risk factors that make narrowed arteries more likely in your kidneys and other parts of your body include:
- High blood pressure
- High cholesterol
- 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
- Kidney failure, requiring treatment with dialysis or a kidney transplant
- Fluid retention in your legs, causing swollen ankles or feet
- Shortness of breath due to a sudden buildup of fluid in the lungs