Kidney (renal) artery disease is a form of peripheral artery disease that reduces blood flow through the renal arteries, which supply blood to the kidneys. It is also called renal artery stenosis (RAS).
You may be evaluated for kidney artery disease if your doctor notices certain signs during a physical examination or routine blood tests. Diagnosing kidney artery disease early can prevent serious damage to your kidneys and other organs, including the heart. If your kidney artery disease is causing high blood pressure, prompt treatment could reduce your risk of suffering a heart attack, stroke, or heart failure.
An evaluation to diagnose kidney artery disease will include:
- A physical examination and medical history
- Blood tests and urine tests to look for signs of kidney problems or damage
- Imaging tests to examine the structure of the kidney arteries and blood flow through them
These tests can determine whether your symptoms are caused by kidney artery disease, and help develop a treatment plan to restore blood flow to the kidneys and prevent future problems.
Medical History & Physical Examination
A medical history includes a complete review of any medical conditions you have (especially risk factors for renal artery disease), surgeries and other procedures you’ve had in the past, and any medications you are taking (including prescription drugs, over-the-counter medications, and dietary supplements).
Because kidney artery disease is usually caused by atherosclerosis, the gradual buildup of fatty deposits on the walls of the arteries, you are at risk for developing the disease if you already have artery problems elsewhere in your body. If you have been diagnosed with PAD, carotid artery disease, or coronary artery disease (especially in two or more of the coronary arteries), your doctor may request further tests to see if your kidney arteries are also narrowed or blocked.
A history of all medications you are taking is also important to diagnose kidney artery disease. Because one of the kidney’s jobs is to control blood pressure, your response to certain blood pressure medications can be a clue that the kidneys are not receiving enough blood. Your doctor will also measure your blood pressure during the physical exam. Severe high blood pressure, especially in younger women, is often the first sign of kidney artery disease.
The following signs of kidney artery disease are often detected during evaluation and treatment for high blood pressure:1
- You are younger than 30 and develop high blood pressure
- You are older than 55 and have severe high blood pressure—higher than 160 mm Hg systolic (top number) or 100 mm Hg diastolic (bottom number)
- Your high blood pressure is rapidly getting worse despite treatment with high blood pressure medications
- You are taking three high blood pressure drugs and your high blood pressure is still not under control
- You have high blood pressure that is causing symptoms of damage to other organs, such as heart failure, vision problems, or nerve problems
- You are taking an ACE inhibitor or ARB to treat high blood pressure and show signs of kidney problems on a blood test
A physical examination can also reveal other clues that your symptoms are caused by kidney artery problems. If you have any of the following signs of kidney artery disease, you may require further tests to look at the renal arteries:2
- A shrunken kidney, or your two kidneys have a size difference of more than 1.5 cm (detected on an imaging test for another condition)
- Sudden unexplained shortness of breath caused by fluid buildup in the lungs (pulmonary edema)
- Unexplained heart failure
- Chest pain (angina) that has not responded to standard treatment
Routine blood tests, performed on a blood sample drawn from your arm, will also be performed to see how your kidneys are working. Kidney function tests to learn what these tests are and what the results mean. Abnormal results on kidney function tests (without another identifiable cause) could mean you need further tests to examine the kidney arteries.
If your doctor finds signs of kidney artery disease during the physical examination or on blood tests, she or he may order imaging tests to examine the shape of your kidney arteries and blood flow through them. These tests can also look at the size and shape of the kidneys themselves.
Imaging tests allow doctors to determine if one or both of your main kidney arteries is narrowed or blocked and how severe the blockage is. In addition to diagnosing kidney artery disease, these imaging tests can also identify problems in nearby blood vessels (such as an aortic aneurysm) and help develop a treatment plan. Noninvasive tests (that do not require breaking the skin or entering the body) that may be used to look at your kidney arteries include:
- Duplex ultrasound – uses reflected sound waves (like those used to view the fetus during pregnancy) to produce a picture of your renal arteries and the blood flowing through them.
- MR Angiogram – a powerful magnetic field produces pictures of your arteries and shows blood flow to the kidneys using an injected dye.
- CT Angiogram – uses x-rays to produce 3-D pictures of the kidney arteries and kidneys. A dye is injected through a vein in your arm during the test to produce detailed images of blood flow.
A duplex ultrasound is usually the first test used to diagnose kidney artery disease because it is fast, inexpensive, and reliable. However, all these tests can accurately diagnose kidney artery disease, and which test is right for you depends on the availability of the different tests at your local hospital, how experienced your doctor is with each test, and some of your own characteristics. The ultrasound test may not be able to provide detailed images in women who are extremely obese. Women with metallic implants or a fear of confined spaces (claustrophobia) cannot undergo MRA. You may not be able to undergo MRA or CTA if you have severe kidney problems or allergies to the contrast dye used during the test.
If noninvasive imaging tests do not provide detailed enough information to plan treatment for kidney artery disease, a contrast angiogram may be required. The angiogram test uses a long thin tube called a catheter that is inserted into a leg artery and guided up to your kidney artery. The catheter injects a dye that is viewable on an x-ray as a video image of blood flow to the kidney.
The contrast angiogram test is the gold standard test for kidney disease and is very safe, but because it involves entering the body there are some risks, and it is usually used only after less invasive tests have been performed. However, if you are already having a contrast angiogram to investigate other artery disease (such as coronary artery disease, aortic disease, or PAD in the legs), your doctor may decide to skip the other imaging tests and look at the kidney arteries during the same angiogram procedure.
Renal Artery Disease Testing Overview
What happens next?
If you have kidney artery disease, you will receive medications to treat high blood pressure and slow the progression of the disease, such as ACE inhibitors, ARBs, calcium channel blockers, and beta-blockers.
If your kidney artery disease is severe (a renal artery is more than 50% blocked) or causing damage to your kidney or other organs, you may need a procedure to restore blood flow to the kidneys, such as angioplasty and stents or renal artery surgery.