Renal Artery 

Stenosis 

National Kidney and Urologic Diseases Information Clearinghouse 

National 

Institute of 

Diabetes and 

Digestive 

and Kidney 

Diseases 

NATIONAL 

INSTITUTES 

OF HEALTH 

U.S. Department 

of Health and 

Human Services 

Renal artery stenosis (RAS) is the narrowing of one or both arteries that carry blood 

to the two kidneys. “Renal” means “kidney” and “stenosis” means “narrowing.” 

RAS can cause high blood pressure and 

reduce kidney function. RAS is often overlooked as a cause of high blood pressure. 

You are at greater risk of developing RAS 

if you smoke or are overweight. RAS is 

most common in men between the ages of 

50 and 70, but women and younger adults 

can also have it. High cholesterol, diabetes, 

and a family history of cardiovascular disease are also risk factors for RAS. High 

blood pressure is both a cause and result 

of RAS. 

What are the kidneys? 

Your two kidneys are bean-shaped organs, 

each about the size of a fist. They are 

located just below the rib cage, one on each 

side of the spine. The arteries that carry 

blood to the kidneys—called the renal 

arteries—branch off directly from the 

abdominal aorta, the main vessel from the 

heart that supplies blood to most of the 

body’s organs. 

Healthy kidneys filter out wastes and extra 

fluid from the blood that passes through 

them. Those wastes and extra fluid become 

urine, which flows from the kidneys to the 

bladder through tubes called ureters. 

Urine is stored in the bladder until released 

through urination. 

What causes RAS? 

In an overwhelming majority of cases, RAS 

is caused by atherosclerosis, hardening of 

the kidney arteries. Thus, RAS develops 

when a material called plaque builds up on 

the inner wall of one or both of the renal 

arteries. The plaque makes the artery wall 

hard and narrow. This narrowing reduces 

or cuts off the blood supply, possibly damaging the kidney. The damaged kidney is 

less efficient at removing wastes and extra 

fluid from the blood. This plaque is similar 

to plaques blocking the arteries supplying 

the heart, which cause heart attacks, and 

In renal artery stenosis, plaque builds up on the inner 

wall of the artery that supplies blood to the kidney. 
those blocking arteries supplying the brain, 

which cause strokes. 

When the kidneys fail, wastes and extra 

fluid build up in the blood. This condition, 

called uremia, causes nausea, headaches, 

fatigue, and swelling in the legs and 

abdomen. With total kidney failure, you 

will need dialysis or a kidney transplant 

to stay alive. 

What are the symptoms 

of RAS? 

RAS can be silent, meaning you will not 

feel any symptoms, until it becomes severe. 

The first sign of RAS may be high blood 

pressure that stays high even when you take 

blood pressure medicine. High blood pressure caused by RAS is called renovascular 

hypertension. Your doctor cannot diagnose 

RAS based on blood pressure alone 

because many conditions can cause your 

blood pressure to rise. If you develop high 

blood pressure suddenly and have no family 

history of high blood pressure, or if your 

blood pressure is difficult to control, your 

doctor might suspect RAS. 

How is RAS diagnosed? 

When blood flows through a narrow vessel, 

it makes a whooshing sound, called a bruit 

(BROO-ee). Your doctor may place a 

stethoscope on the front or the side of your 

abdomen to listen for this sound. The 

absence of this sound, however, by no 

means excludes the possibility of RAS. 

For a more accurate diagnosis, your doctor 

may order an ultrasound or an angiogram 

to get a picture of the artery. An ultrasound uses harmless sound waves to create 

images of internal organs; it does not 

require intravenous injection or oral 

administration of any substances. An 

angiogram is a special kind of x ray in which 

a thin, flexible tube called a catheter is 

threaded through the large arteries, often 

from the groin, to the artery of interest— 

in this case, the renal artery. A special 

dye is injected through the catheter so the 

renal artery will show up clearer on the 

x ray. The advantage of angiograms is that 

they give a better picture and therefore 

more accurate diagnosis of RAS; the 

disadvantage is that this procedure is 

more invasive. 

More recently, doctors have been using 

computerized tomography (CT) scans and 

magnetic resonance angiograms (MRA) to 

evaluate RAS. CT scans use multiple x-ray 

images combined by a computer to create a 

three-dimensional image of your internal 

organs. MRAs use moving magnets to 

create similar three-dimensional images. 

CT scans and MRAs are less invasive 

than conventional angiograms, but the 

results may not be as clear or accurate. 

Researchers are exploring ways to improve 

these imaging techniques and make them 

more reliable for evaluating RAS. 

How is RAS treated? 

Approaches to RAS are threefold: 

•	 preventing RAS from getting worse 

•	 treating high blood pressure that
 

results from RAS
 

•	 relieving the blockage of the renal
 

arteries
 

2	 Renal Artery Stenosis 
Lifestyle Changes 

The first step in treating RAS is making 

lifestyle changes that promote healthy 

blood vessels in general. Exercising, controlling your weight, and choosing healthy 

foods will help keep your arteries clean and 

flexible. If you smoke, quitting is one of 

the best things you can do to save your 

kidneys and other organs. 

Blood Pressure Medicines 

RAS causes high blood pressure, which can 

damage the kidneys. Damaged kidneys, in 

turn, can make your blood pressure even 

higher. If left uncontrolled, this vicious 

cycle can lead to kidney failure and 

damage the heart and blood vessels 

throughout the body. 

Controlling renovascular hypertension is 

often difficult but usually achievable. It 

may require two or more different kinds of 

blood pressure medicine. Blood pressure 

medicines work in different ways. 

Sometimes, by combining two or more 

blood pressure medicines that work in 

different ways, you may be able to control 

your blood pressure and stop the progression of kidney failure. Each type of blood 

pressure medicine has its own potential 

side effects; therefore, the choice of 

medicine is best determined by you and 

your doctor. 

In addition to blood pressure medicines, 

your doctor may prescribe a cholesterollowering drug to prevent the plaques 

from forming in the arteries, and a bloodthinner, such as aspirin, to help the blood 

flow more easily through the arteries. 

Surgery 

If RAS advances until the artery is nearly or 

completely blocked, you may need surgery 

to open up the flow of blood to the kidney. 

Different types of surgery for RAS include 

the following: 

•	 Angioplasty and stenting. Angioplasty 

is a procedure in which a catheter is 

put into the renal artery, usually 

through the groin, just as in a conventional angiogram. In addition, for 

angioplasty, a tiny balloon at the end 

of the catheter can be inflated to 

flatten the plaque against the wall of 

the artery. Then your doctor may 

position a small mesh tube, called a 

stent, to keep plaque flattened and 

the artery open. 

•	 Endarterectomy. In an endarterectomy, a vascular surgeon cleans out 

the plaque, leaving the inside lining of 

the artery smooth and clear. 

•	 Bypass surgery. To create a bypass, a 

vascular surgeon uses a vein or synthetic tube to connect the kidney to the 

aorta. This new path serves as an alternate route for blood to flow around the 

blocked artery into the kidney. 

Hope Through Research 

The National Institute of Diabetes and 

Digestive and Kidney Diseases (NIDDK) 

conducts and supports research into many 

kinds of kidney disease, including RAS. 

Researchers supported by the NIDDK are 

exploring ways to improve the diagnosis of 

this disease using new MRA techniques 

that provide more information about blood 

flow to the kidney and how well the kidney 

is functioning. These studies will point the 

way to more effective treatments for RAS 

and healthy kidneys. 

3	 Renal Artery Stenosis 
For More Information

American Urological Association

Foundation

1000 Corporate Boulevard, Suite 410

Linthicum, MD 21090

Phone: 1–866–RING–AUA (746–4282) 

or 410–689–3700

Email: patienteducation@auafoundation.org

Internet: www.auafoundation.org

www.UrologyHealth.org

Society for Vascular Surgery

633 North St. Clair, 24th Floor

Chicago, IL 60611

Phone: 1–800–258–7188 or 312–202–5600

Email: vascular@vascularsociety.org

Internet: www.vascularweb.org

You may also find additional information

about this topic by visiting MedlinePlus at

www.medlineplus.gov.

National Kidney and

Urologic Diseases

Information Clearinghouse

3 Information Way

Bethesda, MD 20892–3580

Phone: 1–800–891–5390

Fax: 703–738–4929

Email: nkudic@info.niddk.nih.gov

Internet: www.kidney.niddk.nih.gov

The National Kidney and Urologic Diseases

Information Clearinghouse (NKUDIC) is a

service of the National Institute of Diabetes

and Digestive and Kidney Diseases (NIDDK).

The NIDDK is part of the National Institutes

of Health of the U.S. Department of Health

and Human Services. Established in 1987,

the Clearinghouse provides information about

diseases of the kidneys and urologic system to

 people with kidney and urologic disorders and

to their families, health care professionals, and

the public. The NKUDIC answers inquiries,

develops and distributes publications, and

works closely with professional and patient

organi zations and Government agencies to

coordi nate resources about kidney and

urologic diseases.

Publications produced by the Clearinghouse are

carefully reviewed by both NIDDK scientists

and outside experts. This fact sheet was

reviewed by Alfred K. Cheung, M.D.,

 University of Utah.

This publication is not copyrighted. The

Clearinghouse encourages users of this fact

sheet to duplicate and distribute as many

copies as desired.

This fact sheet is also available at 

www.kidney.niddk.nih.gov.

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES

National Institutes of Health

NIH Publication No. 07–6020

May 2007