What is renal artery stenosis?
It is narrowing of the artery that supplies blood to the kidneys. That might results in restriction of blood flow to the kidneys and may lead to high blood pressure (hypertension) and reduced kidney function (kidney failure).
What causes renal artery stenosis?
In most cases it is caused by build up of cholesterol and lipid on the lining of arteries (atherosclerosis). This is the same disease that cause heart attack and angina when it affect arteries of the heart. Occasionally other things are responsible:
- In fibromuscular dysplasia an abnormality of the artery causes progressive narrowing of the renal artery during growth. Patients diagnosed with this condition are usually young.
- Rarely other things may be responsible. For instance damage caused by trauma to the kidneys or radiotherapy, or rare causes of inflammation such as Takayasu’s disease.
When is renal artery stenosis suspected?
Renal artery stenosis usually has no symptoms. However the diagnosis is considered when there are clues such as:
- Blood pressure is unusually difficult to control, or new, or severe in a young person.
- There is a kidney damage without evidence of kidney inflammation, but in the presence of diseased arteries elsewhere, especially in the legs (e.g. intermittent claudication, which often causes pain in the calves on walking). Signs of disease in the arteries can include a bruit (a sound with a stethoscope suggesting a narrowed artery), which may be heard over the abdomen in the case of renal artery stenosis.
- Kidneys are asymmetrical (one side shrunken, other side normal) on ultrasound or other kind of investigation. More about ultrasound examination of the kidney. Kidney asymmetry can have other causes too though, such as reflux nephropathy.
How is the diagnosis made?
The most accurate test is renal arteriography, but it requires injection of contrast medium (‘dye’) directly into an artery. The dye can have side-effects, and arteriography has some risks too. More information about renal angiography.
Techniques for showing the arteries to the kidney without going into arteries (‘non-invasive’ tests) are improving very rapidly. These include
- MRA (magnetic resonance angiography)
- CT angiography More information
What are the treatment options?
The best treatment depends on a number of factors:
- your overall health
- the severity of your high blood pressure
- your kidney function
- the severity of the narrowing and the risks of treating it (see below)
You will need to discuss your personal circumstances with your medical team.
Blood pressure: Tight control of high blood pressure with medication is usually the first thing to do.
Kidney damage: If kidney failure develops or gets worse despite treatment, all the options for dealing with this must be considered. More information below
General treatment for patients with atherosclerosis
Other measures that may help not only kidney arteries but any other arteries in your body affected by atherosclerosis include the following:
- stop smoking
- daily low dose aspirin
- lower blood cholesterol level – medication is often justified
In addition, a healthy diet and exercise are likely to be helpful to general health.
Drugs to be avoided in patient with renal artery stenosis
Some medications can reduce kidney blood flow. This can lead to trouble if the blood supply is already reduced by renal artery stenosis, as kidney function can be severely reduced. The major medications that can cause this problem are:
- Non Steroid Anti Inflammatory Drugs (NSAIDs)
- Angiotension Converting Enzyme Inhibitors (ACE Inhibitors; usually there must be narrowing of arteries to both kidneys to have this effect)
More information about chronic kidney disease and its treatment
More information about End stage renal failure and its treatment
More information on high blood pressure and the kidney from EdREN. Describes how kidney disease often goes with high blood pressure, and why patients with kidney disease should be treated to lower blood pressures than other people.
Acknowledgements: The authors of this page were Fathi Lajili and Neil Turner. It was first published in June 2005 and reviewed by Paddy Gibson in April 2010. The date is was last modified is shown in the footer.