Causes

When the arteries that carry blood to your kidneys become narrow, less blood flows to the kidneys. The kidneys mistakenly respond as if your blood pressure is low and give off hormones that tell the body to hold on to more salt and water. This causes your blood pressure to rise.

Renal artery stenosis is a narrowing or blockage of the artery that supplies blood to the kidneys.

The most common cause of renal artery stenosis is hardening of the arteries (atherosclerosis) from high cholesterol. This problem occurs when a sticky, fatty substance called plaque builds up on the inner lining of the arteries. The plaque may slowly narrow or even block the renal (kidney) artery.

Risk factors for atherosclerosis include high blood pressure, smoking, diabetes, high cholesterol, heavy alcohol use, cocaine abuse, and increasing age.

Fibromuscular dysplasia is another cause of renal artery stenosis. It is often seen in women under age 50 and tends to run in families.Fibromuscular dysplasia is caused by abnormal growth of cells in the walls of the arteries leading to the kidneys. This also leads to narrowing or blockage of these arteries.

Symptoms

People with renovascular hypertension may have a history of high blood pressure that is severe and hard to control with medication.

Symptoms of renovascular hypertension include:

• High blood pressure at a young age
• High blood pressure that suddenly gets worse or is difficult to control
• Kidneys that are not working well, which often occurs suddenly
• Narrowing of other arteries in the body, such as to the legs, the brain, the eyes and elsewhere
• Sudden buildup of fluid in the air sacs of the lungs (pulmonary edema)

If you have a severe headache, nausea or vomiting, bad headache, confusion, changes in your vision, or nosebleeds you may have a severe and dangerous form of high blood pressure called malignant hypertension.

Exams and Tests

The health care provider may hear a "whooshing" noise, called a bruit, when placing a stethoscope over your belly area.

The following blood tests may be done:

• Cholesterol level
• Renin and aldosterone levels
• Bun - blood test
• Creatinine - blood test
• Potassium - blood test
• Creatinine clearance

Imaging tests may be done to see if the kidney arteries have narrowed. They include:

• Angiotensin converting enzyme (ACE) inhibition renography
• Doppler ultrasound of the renal arteries
• Magnetic resonance angiography (MRA)
• Renal arteriography

Treatment

High blood pressure caused by narrowing of the arteries that lead to the kidneys (renovascular hypertension) is often difficult to control.

Medications are needed to help control blood pressure. There are a variety of high blood pressure medications available. You and your doctor will decide which type is best for you. often more than one type may be needed.

• Everyone responds to medicine differently. Your blood pressure should be checked frequently. The amount and type of medicine you take may need to be changed from time to time.
• Ask your doctor what blood pressure measurement is appropriate for you.
• Take all medicines in the exact way your doctor prescribed them.

Have your cholesterol checked and treated. If you have diabetes, heart disease, or hardening of the arteries somewhere else in your body, your "bad" (LDL) cholesterol should be lower than 100 mg/dL.

Lifestyle changes are important:

• Eat a heart-healthy diet.
• Exercise regularly, at least 30 minutes a day (check with your doctor before starting).
• If you smoke, quit. Find a program that will help you stop.
• Limit how much alcohol you drink: 1 drink a day for women, 2 a day for men.
• Limit the amount of sodium (salt) you eat. Aim for less than 1,500 mg per day. Check with your doctor about how much potassium you should be eating.
• Reduce stress. Try to avoid things that cause stress for you. You can also try meditation or yoga.
• Stay at a healthy body weight. Find a weight-loss program to help you, if you need it.

Further treatment depends on what causes the narrowing of the kidney arteries. For example, your doctor may recommend a procedure called angioplasty with stenting if you have this condition and it is not well-managed with medications. For information, see: Stent.

These procedures may be an option if you have:

• Severe narrowing of the renal artery
• Blood pressure that cannot be controlled with medicines
• Kidneys that are not working well and are becoming worse.

However, experts are not certain which patients should have these procedures.

Possible Complications

If your blood pressure is not well controlled, you are at risk for the following complications:

• Aortic aneurysm
• Heart attack
• Heart failure
• Chronic kidney disease
• Stroke
• Vision problems
• Poor blood suppy to the legs

When to Contact a Medical Professional

Call for an appointment with your health care provider if you think you have high blood pressure.

Call your health care provider if you have renovascular hypertension and symptoms get worse or do not improve with treatment. Also call if new symptoms develop.

Prevention

Preventing atherosclerosis or hardening of the arteries may prevent rental artery stenosis. You can do this by following these tips:

• Lose weight if you are overweight.
• Ask your doctor about your smoking and alcohol use.
• Control your blood sugar if you have diabetes.
• Make sure your doctor is monitoring your blood cholesterol levels.
• Eat a heart healthy diet (See: Heart disease and diet)
• Get regular exercise. Check with your doctor before starting an exercise program.

Alternative Names

Renal hypertension; Hypertension - renovascular; Renal artery occlusion; Stenosis - renal artery; Renal artery stenosis

References

Victor RG. Systemic hypertension: Mechanisms and diagnosis. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 45.

Kaplan NM. Systemic hypertension: Therapy. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 46.

Dworkin LD, Murphy T. Is there any reason to stent atherosclerotic renal artery stenosis? Am J Kidney Dis. 2010 Aug;56(2):259-63.

U.S. Preventive Services Task Force. Screening for high blood pressure: U.S. Preventive Services Task Force reaffirmation recommendation statement. Ann Intern Med. 2007;147(11):783-786.

Update Date: 5/23/2012

Reviewed by: David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc., and Michael A. Chen, MD, PhD, Assistant Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington.