Renal Artery Stenosis
Renal artery stenosis (RAS, sometimes also called renal artery disease or kidney stenosis) occurs when the two main vessels that deliver blood to the kidneys become stiff or narrowed due to vascular disease. RAS is a type of atherosclerosis or hardening of the arteries, which occurs when fatty cholesterol plaques build up inside artery walls. The kidneys perform several key functions in the body, including regulating blood pressure and removing waste and toxins from the blood. Renal artery disease can reduce the amount of blood that’s able to flow into the kidneys, which can raise blood pressure and allow toxins to build up in the body’s tissues.
Anyone can develop RAS, but the risk increases with age. The risk factors for any kind of atherosclerosis also apply to RAS, which means anyone with high cholesterol, hypertension, insulin resistance, or a family history of cardiovascular disease may be at higher risk for renal artery stenosis. Other medical conditions, most notably fibromuscular dysplasia (FMD), can also cause renal artery stenosis. FMD is a rare condition that affects more women than men between the ages of 25 and 50.
Renal artery stenosis may not produce symptoms until it reaches a severe stage. When RAS becomes symptomatic, it often results in decreased kidney function, such as changes in urination or swelling of the feet and legs. RAS also can cause high blood pressure. Because the symptoms of RAS mimic those of other cardiovascular diseases, renal artery stenosis diagnosis often occurs during an investigation into a related condition like unexplained hypertension.
As a type of atherosclerosis, renal artery stenosis may be preventable by following a heart-healthy lifestyle. Left untreated, renal stenosis can cause kidney damage or kidney failure that requires dialysis or an organ transplant. Usually, the effects of RAS develop over a long period of time and do not require emergency medical treatment.
The symptoms of renal artery stenosis can be subtle and develop over many years. This fact makes an early diagnosis less likely. Most of the time, the symptoms of RAS are related to decreased kidney function.
Common symptoms of renal artery stenosis
The most common symptoms of renal artery stenosis are:
Atherosclerosis is the main cause of renal artery stenosis. Atherosclerosis develops from the buildup of plaques made up of substances like fats, cholesterol, and other materials in the blood. These plaques cause artery walls to become thick and stiff, and they also reduce the size of the artery’s lumen—the opening where blood passes through.
Rental artery stenosis also can be caused by a rare condition called fibromuscular dysplasia. FMD triggers the production of abnormal cells in the walls of arteries throughout the body, which in turn makes them narrow and stiff. Researchers do not yet know the cause of FMD, but it disproportionately affects women and people between the ages of 25 and 50.
The risk factors for renal artery stenosis are the same as for coronary artery disease (heart disease) and carotid artery disease. All these cardiovascular diseases are caused by atherosclerosis. Factors that increase the risk of atherosclerotic vascular damage and renal artery stenosis include:
- Age older than 45 for men and 55 for women
- Diabetes or insulin resistance
- Family history of fibromuscular dysplasia
- High blood pressure
- High cholesterol levels
- High fat, low-fiber diet or a diet that is high in salty and smoked foods
- Overweight or obesity
- Sedentary lifestyle
Reducing your risk of RAS
You may be able to lower your risk of renal artery stenosis by:
- Controlling your blood sugar levels if you have diabetes
- Eating a diet that is low in fat and salt, and high in fiber and fruits and vegetables
- Maintaining a healthy weight
- Participating in a regular exercise program
- Quitting smoking
- Treating any coexisting cardiovascular disease like high blood pressure or high cholesterol
Renal artery stenosis treatment aims to slow the progression of the disease. Your specific treatment options will depend on the severity of the kidney stenosis and your overall health. Vascular surgery generally is not considered except in extreme cases or when FMD is the cause. Common renal artery stenosis treatments include:
- Lifestyle changes to increase your intake of fiber, fruits and vegetables, along with getting regular physical activity
- Medicines to control blood pressure or reduce cholesterol levels
- Vascular surgery including placing stents in the renal arteries to hold them open
Left untreated, renal artery stenosis can cause kidney failure, leading to the need for dialysis or even a kidney transplant. These complications usually develop over a long period of time, which gives you the opportunity to intervene with lifestyle changes and medical treatments before stenosis becomes severe enough to require surgery or cause kidney damage.