--- title: Renal artery stenosis description: What renal artery stenosis (narrowing of a kidney artery) is, why it raises blood pressure and harms the kidney, how atherosclerosis differs from fibromuscular dysplasia, how the narrowing is found, which treatment approaches clinical guidelines describe, and when to call an ambulance. type: disease aliases: - RAS - narrowing of the renal artery - renovascular hypertension - renovascular disease - atherosclerotic renal artery stenosis - renal artery atherosclerosis - fibromuscular dysplasia - FMD sources: - tier: guideline org: minzdrav-rf title: Артериальная гипертензия у взрослых year: 2024 doi: 10.15829/1560-4071-2024-6117 url: https://cr.minzdrav.gov.ru/view-cr/62_3 - tier: guideline org: esc title: 2024 ESC Guidelines for the management of peripheral arterial and aortic diseases year: 2024 doi: 10.1093/eurheartj/ehae179 url: https://doi.org/10.1093/eurheartj/ehae179 - tier: guideline org: esc title: 2024 ESC Guidelines for the management of elevated blood pressure and hypertension year: 2024 doi: 10.1093/eurheartj/ehae178 url: https://doi.org/10.1093/eurheartj/ehae178 - tier: reference org: msd-manuals title: Renovascular Hypertension (MSD Manual Professional Version) year: 2025 url: https://www.msdmanuals.com/professional/cardiovascular-disorders/hypertension/renovascular-hypertension - tier: reference org: msd-manuals title: Renal Artery Stenosis and Occlusion (MSD Manual Professional Version) year: 2025 url: https://www.msdmanuals.com/professional/genitourinary-disorders/renovascular-disorders/renal-artery-stenosis-and-occlusion - tier: reference org: msd-manuals title: High Blood Pressure (MSD Manual Consumer Version) year: 2025 url: https://www.msdmanuals.com/home/heart-and-blood-vessel-disorders/high-blood-pressure/high-blood-pressure - tier: reference org: statpearls title: Fibromuscular Dysplasia year: 2023 url: https://pubmed.ncbi.nlm.nih.gov/29630256/ sources_checked: 2026-10-14 review: null --- Renal artery stenosis is a decrease in blood flow through one or both renal arteries or their branches. Its main consequence is renovascular hypertension: raised blood pressure due to partial or complete blockage of the renal arteries. It is one of the causes of secondary hypertension, that is, high blood pressure with a specific cause. Most people with high blood pressure have no such separate cause; for high blood pressure in general, see the article on [hypertension](../hypertension/). The Russian Ministry of Health guideline and the ESC list renovascular disease among the common causes of secondary hypertension, while MSD estimates that it is rare among all people with high blood pressure.

The diagram shows the aorta, the two renal arteries and the two kidneys. The origin (ostium) of a renal artery is where it branches off the aorta. For comparison, the arteries are drawn with an even lumen and the kidneys are the same size.

Most often the artery is narrowed by an atherosclerotic plaque at its origin or in its first part. The narrowing makes the kidney beyond it release renin; this leads to the production of angiotensin II, which narrows small arteries, and blood pressure rises. With long-standing narrowing the kidney shrinks. A less common cause is fibromuscular dysplasia: most often, in the middle and far parts of the artery, narrowed segments alternate with widened ones like a string of beads.

## Why it happens The two main causes of renal artery narrowing are atherosclerosis and fibromuscular dysplasia (FMD); atherosclerosis is much more common. In atherosclerosis a plaque grows in the artery wall, usually right at the start of the renal artery. This kind of stenosis is more common in older people, in men, in smokers, in people with diabetes and in people with atherosclerosis of other arteries, especially the leg arteries. That is why other arteries are checked as well. See the articles on [coronary heart disease](../coronary-heart-disease/), [peripheral artery disease](../peripheral-artery-disease/), [carotid artery stenosis](../carotid-artery-stenosis/) and [dyslipidaemia](../dyslipidemia/). FMD is neither atherosclerosis nor inflammation: the artery wall thickens unevenly. It is more common in young and middle-aged women, but it can occur at any age and in men, and it is more common in close relatives of people with FMD. FMD often affects more than one artery: besides the renal arteries, often the carotid arteries; it can also show itself as a stroke in a young adult. Rarely, the renal artery is narrowed by other diseases, such as [Takayasu arteritis](../takayasu-arteritis/), [Kawasaki disease](../kawasaki-disease/) or [aortic dissection](../aortic-dissection/), or by injury, pressure from a tumour or radiotherapy to the abdomen. Renovascular hypertension (ICD-10 I15.0) is hypertension due to partial or complete occlusion of one or more renal arteries or their branches; the stenosis causes it by stimulating release of renin from the juxtaglomerular cells of the affected kidney. As a rule only a haemodynamically significant stenosis raises blood pressure; renal artery angioplasty is not recommended in patients without confirmed haemodynamically significant stenosis (ESC HTN, III A). Atherosclerosis mainly affects the ostium and proximal segment of the renal artery and is usually bilateral; FMD is commonly unilateral and affects the distal main renal artery and the intrarenal branches. The Russian Ministry of Health guideline distinguishes the more common multifocal FMD, with alternating stenoses and dilatations in the middle and distal segments of the artery (the "string of beads" sign), and focal FMD. More than half of patients with FMD have disease in several vascular beds, with dissection, aneurysms or marked tortuosity of the arteries. The share of atherosclerosis and FMD among causes, and how common stenosis is in people with hypertension, differ between sources. According to MSD, renovascular disease accounts for less than 1% of all cases of hypertension; the Russian Ministry of Health guideline states that the prevalence of atherosclerotic renal artery disease varies with the population and is highest in severe or resistant hypertension. ## Symptoms The stenosis itself usually causes no symptoms. Most often blood pressure gives it away: it rises suddenly, quickly becomes higher than before, or stays high despite several medicines. High blood pressure that starts at an unusual age, when young or, on the contrary, when older, also raises suspicion. Other clues are worsening kidney function without a clear cause, kidneys of different sizes on tests, repeated sudden attacks of breathlessness from fluid on the lungs, or [heart failure](../heart-failure/) without a clear cause. Long-standing narrowing can lead to chronic kidney disease, whose signs develop slowly. The ESC (PAAD) lists clinical signs suggestive of renal artery disease: hypertension onset before 30 years of age; severe hypertension after the age of 55 years when associated with CKD or heart failure; hypertension and abdominal bruit; rapid and persistent worsening of previously controlled hypertension; resistant hypertension; hypertensive crisis; new azotaemia or worsening of renal function after treatment with RAAS blockers; unexplained atrophic kidney, discrepancy in kidney size or unexplained renal failure; flash pulmonary oedema. A systolic-diastolic bruit in the epigastrium is almost pathognomonic, but according to MSD it is present in only about half of patients with FMD and is rare in renal atherosclerosis. A marked rise in creatinine on RAAS inhibitors calls for investigation to exclude renovascular disease. ## How it is diagnosed If a doctor suspects stenosis, the first test is usually an ultrasound of the kidneys with duplex scanning of the renal arteries: it shows the size of the kidneys and the blood flow in the arteries. If the ultrasound supports the suspicion or is inconclusive, CT or MR angiography is done. The most accurate test is angiography with a catheter passed into the artery; it is done when other tests have not given an answer and suspicion is high, or before a procedure on the artery. Young people with high blood pressure are checked for secondary causes, and after a first hypertensive crisis the cause of the high blood pressure is looked for in everyone. ESC (PAAD): duplex ultrasound is recommended as the first-line imaging modality in patients with suspected renal artery stenosis (I B); when duplex ultrasound suggests stenosis or is inconclusive, MRA or CTA is recommended (I B). The ESC (HTN) recommends comprehensive screening for secondary hypertension in adults diagnosed with hypertension before the age of 40 years (I B). Non-invasive testing is less reliable for FMD because the lesion typically involves the intrarenal portion of the renal artery; renal angiography is the definitive test. The Russian Ministry of Health guideline recommends that all patients with FMD have whole-body CT angiography (MR angiography if contraindicated) at least once. Before deciding on revascularisation in atherosclerotic stenosis, the ESC (PAAD) recommends assessing clinical high-risk features and kidney viability (I B). ## How it is treated Everyone with renal artery stenosis needs medicines: they control blood pressure and protect the kidneys, and in atherosclerotic stenosis they are the basis of treatment and lower the overall risk of heart and blood vessel complications, as in atherosclerosis of other arteries. The doctor chooses the medicines and doses. Do not stop or change your medicines on your own. In atherosclerotic stenosis, widening the artery is not recommended for everyone: in a large trial, placing a stent did not improve outcomes compared with medicines alone. Widening the artery from inside (angioplasty with a stent) is discussed for some people with high-risk features: repeated fluid on the lungs or heart failure, blood pressure that does not come down with medicines, worsening kidney function, narrowing of both renal arteries or of the artery to a single kidney. In FMD with high blood pressure, guidelines suggest considering balloon angioplasty: the narrowed segment is widened with a balloon from inside the artery. Guidelines word the question of a stent differently, but all of them allow one only in special cases, for example a complication of the procedure; details are in the student section. After angioplasty, blood pressure returns to normal in some people, more often in young people whose high blood pressure began recently. If widening the artery from inside is technically difficult or has failed, open surgery (bypass) is sometimes done. Whether a procedure is needed, and which one, is decided by the doctor together with the patient. Russian Ministry of Health guideline: the aims of medical treatment in renal artery atherosclerosis are cardiovascular risk reduction and nephroprotection, with blood pressure control as the key; ACE inhibitors or ARBs are named first-line drugs but are contraindicated in bilateral renal artery stenosis or stenosis of the artery to a solitary kidney. The ESC (PAAD) recommends that antihypertensive treatment in unilateral stenosis include ACE inhibitors/ARBs (I B), and in bilateral stenosis allows them (IIb B) if close monitoring of renal function is feasible; here the guidelines differ. Specific drugs and doses are not given here. Routine revascularisation is not recommended in unilateral atherosclerotic stenosis (ESC PAAD, III A); in the CORAL trial, stenting did not improve outcomes compared with medical management. The ESC (PAAD) suggests considering revascularisation (IIa B) in severe atherosclerotic stenosis with high-risk features and signs of kidney viability; in unilateral stenosis, only once optimal medical therapy has been established. The ESC (HTN) allows angioplasty and stenting of haemodynamically significant atherosclerotic stenosis in high-risk patients, for example with recurrent heart failure or sudden-onset flash pulmonary oedema despite maximally tolerated medical therapy, resistant hypertension, bilateral stenosis or stenosis in a solitary viable kidney (IIb C). FMD: ESC (HTN), angioplasty without stenting in hypertension with haemodynamically significant stenosis (IIa C); ESC (PAAD), with high-risk features and signs of kidney viability, primary balloon angioplasty with stenting only as a bailout (IIa B); the Russian Ministry of Health guideline does not recommend stenting in renal FMD except for flow-limiting dissection during the procedure or a renal artery aneurysm. The ESC (PAAD) suggests considering open surgical revascularisation for complex anatomy or after failed endovascular revascularisation (IIa B). ## When to call an ambulance Renal artery stenosis itself often causes no symptoms for a long time, but it can show itself as an emergency, such as sudden fluid on the lungs (flash pulmonary oedema) or a hypertensive crisis. A hypertensive crisis, a marked rise in blood pressure with acute organ damage, is often life-threatening and needs immediate help; its signs are described in a separate [article](../hypertensive-crisis/). If these signs appear, call your local emergency number immediately (112 in the EU, 911 in the US and Canada, 999 in the UK). Sudden, steady, aching pain in the side or abdomen, especially with fever, nausea and vomiting, blood in the urine or a sharp fall in the amount of urine, can mean a sudden blockage of the renal artery, most often by a clot that can travel, for example, from the heart in [atrial fibrillation](../atrial-fibrillation/). Call an ambulance for these signs too. FMD can show itself as a stroke in a young adult. At any sign of stroke, call your local emergency number straight away (112 in the EU, 911 in the US and Canada, 999 in the UK); how to recognise them is described in the article on [carotid artery stenosis](../carotid-artery-stenosis/). As with any heart or blood vessel condition, call an ambulance for fainting, chest pain or severe breathlessness: this is the site's general safety rule, repeated at the bottom of every page.