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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• What are the renal arteries?
• What is renal artery stenosis?
• What are the causes of renal artery stenosis?
• How common is renal artery stenosis?
• What are the symptoms of renal artery stenosis?
• What problems does renal artery stenosis cause?
• Who should be screened for renal artery stenosis?
• How is renal artery stenosis diagnosed?
• What are the common imaging tests to evaluate renal artery stenosis?
• What functional tests are used for the diagnosis of renal artery stenosis?
• What are medical treatments for renal artery stenosis?
• What surgical procedures are available for renal artery stenosis?
• Which patients can benefit from surgical procedures for renal artery stenosis?
• Renal Artery Stenosis At A Glance
• Patient Comments: Renal Artery Stenosis - Cause
• Patient Comments: Renal Artery Stenosis - Diagnosis
• Find a local Nephrologist in your town
• Renal Artery Stenosis Index

In general, renal artery stenosis is not associated with any obvious or specific symptoms. Suspicious signs for renal artery stenosis include:

• high blood pressure that responds poorly to treatment;
  
  
• severe high blood pressure that develops prior to age 30 or greater than age 50;
  
  
• an incidental finding (discovered through routine tests or tests performed for another condition) of one small kidney compared to a normal sized one on the other side.

Typically, unilateral (one-sided) renal artery stenosis may be related to high blood pressure whereas bilateral (two-sided) renal artery stenosis is more often related to diminished kidney function.

When the circulating blood volume becomes depleted as a result of, for example, dehydration or bleeding, the blood flow to the kidneys is likewise reduced. The normal physiologic reaction to a decrease in blood flow to the kidneys is a complex hormonal response by the kidneys, called the renin-angiotensin-aldosterone system.

This hormonal system is activated as a defense against low blood pressure and low circulating blood volume. The kidney senses a possible decrease in the circulating blood when blood flow through these vessels is reduced. As a result, there are increased blood levels of the hormone angiotensin 2, which causes narrowing of the small blood vessels in the kidneys.

This, together with increased blood aldosterone levels (another hormone), promotes salt retention by the kidneys, and works to maintain blood pressure and restore blood volume. Accordingly, this hormonal system is protective in response to reduced circulation of blood to the kidneys that is caused either by volume depletion, as described, or by reduced blood pressure.

This otherwise normal hormonal response can become abnormal (pathologic) when the decreased blood flow to the kidneys results from a narrowing of diseased renal arteries. In this situation, the kidneys receive less blood flow, which then signals a sense of depletion of the circulating blood volume, despite the fact that the blood volume is actually normal. So, the diminished renal blood flow, by stimulating the production of angiotensin 2 and aldosterone, can lead to an abnormal increase of blood pressure (renovascular hypertension).