Renal artery stenosis: symptoms, causes, tests and treatment in the UK

Each kidney receives blood through a renal artery that branches from the main artery in the abdomen. When one or both of these arteries narrow, less blood reaches the kidney. Kidney Research UK says that less oxygen-rich blood reaching the kidney tissue can harm kidney health over time.

Kidney Research UK describes renal artery stenosis as one or more of the arteries supplying the kidneys becoming narrower, and says it can cause high blood pressure and lead to chronic kidney disease (CKD). The term stenosis simply means narrowing. It can affect one side or both, and the degree of narrowing varies widely, which is why some people are monitored while others need treatment.

The most common cause is atherosclerosis. The NHS explains that atherosclerosis is where fatty deposits build up in the arteries and cause them to narrow. Risk factors the NHS lists include being over 50, smoking, high cholesterol, high blood pressure, diabetes or kidney disease, overweight or obesity, close relatives with cardiovascular disease, and being of Black African, African Caribbean or South Asian origin. Kidney Research UK lists age over 65, smoking, high blood pressure, high cholesterol and a family history of heart and vascular disease.

Less common causes include fibromuscular dysplasia, which causes thickening of the artery walls, and other diseases that affect arteries such as Takayasu's arteritis, according to Kidney Research UK. The NHS says atherosclerosis, left without lifestyle changes and medical treatment, may get worse and can cause heart attacks, stroke and peripheral arterial disease, so the same risk factors matter for the heart and brain as well as the kidneys.

Kidney Research UK says that in most cases renal artery stenosis has no symptoms. Where there are symptoms, they depend on how seriously blood flow is affected and can include high blood pressure and symptoms of chronic kidney disease. The NHS says high blood pressure does not usually cause any symptoms and that many people have it without realising it, which is why it is often found at a routine check. Rarely it can cause headaches, blurred vision or chest pain.

For chronic kidney disease the NHS lists tiredness, swollen ankles, feet or hands, shortness of breath, feeling sick and blood in the urine as symptoms at a more advanced stage, and says to see a GP for persistent or worrying symptoms. The NHS advises getting help from NHS 111 if you often have headaches or blurred vision, or chest pain that comes and goes. Call 999 if you have sudden chest pain that does not go away, pain spreading to the arm, neck, jaw, stomach or back, or chest pain with sweating, sickness, light-headedness or breathlessness. Signs of stroke, such as a drooping face, weak arm or difficulty speaking, also need 999.

Kidney Research UK says a doctor will look at your medical and family history, test results and symptoms, and may listen with a stethoscope for the sound of blood passing through the kidney arteries in the abdomen, as a narrowing can sometimes be heard. Urine and blood tests are used to assess kidney function. The NHS says CKD is diagnosed using blood and urine tests, which are used to tell the stage of kidney disease.

To diagnose renal artery stenosis itself, Kidney Research UK says a medical image is needed. This can include a special ultrasound, CT or MRI scan, sometimes with contrast injected to see the arteries better. The sources reviewed here do not set out detailed criteria for when a scan of the kidney arteries is arranged, so ask your doctor why it is being considered.

Blood pressure is measured with a cuff, and the NHS says that a reading of 140/90 or higher in a clinic, or 135/85 or higher at home, is usually considered high, and that home or 24-hour monitoring may be used to confirm it.

Kidney Research UK says treatment depends on the cause of the stenosis and how much it has narrowed the artery. Some patients are monitored with regular imaging. If you have high blood pressure and high cholesterol you will be given medicines and lifestyle advice to reduce them, along with medicines to try to prevent the artery narrowing further.

Some patients need a procedure to widen the artery. Kidney Research UK describes angioplasty, in which a narrow flexible tube is inserted into a blood vessel, usually in the groin, wrist or arm, and guided by X-ray to the narrowed artery. A small balloon is inflated to stretch the artery and restore blood flow, and in some cases a metal mesh tube called a stent is placed to keep it open.

Kidney Research UK says persistent high blood pressure can strain and harm organs including the kidneys, heart and brain, and that less blood reaching the kidney can lead to chronic kidney disease, which in some cases progresses to kidney failure, though this is uncommon. The NHS says that most people with CKD can control their condition with medicine and regular check-ups, and that CKD only progresses to kidney failure in around 2 in 100 people with the condition.

The NHS notes that even mild CKD increases the risk of cardiovascular disease, which includes heart attack and stroke, and that healthy lifestyle changes and medicine can help reduce that risk. The NHS says there are currently no treatments to reverse atherosclerosis, but medicines can lower the risk of heart attack and stroke. For many people, the long-term focus is therefore blood pressure control, cholesterol treatment, stopping smoking and regular kidney tests.

Some medicines can affect the kidneys, and the NHS lists regular use of non-steroidal anti-inflammatory drugs (NSAIDs) and lithium among causes of CKD, so check with a pharmacist or doctor before taking painkillers regularly, particularly if you have kidney disease.

On the NHS, a GP checks blood pressure, kidney function and cholesterol, and may refer to a kidney specialist (nephrologist) or a vascular specialist when stenosis is suspected. Imaging and any angioplasty are usually done in a hospital with interventional radiology or vascular services. Ongoing blood pressure and kidney monitoring is often shared between the GP and the hospital.

Private care can speed up scans and specialist appointments, and the tests and procedures are the same. Kidney Research UK says treatment depends on the cause and on how much the artery has narrowed, so it is reasonable to ask a specialist why a procedure is being recommended, what it is expected to achieve and what the alternatives are.