What is fibromuscular dysplasia (FMD)?
Fibromuscular dysplasia (FMD) is a rare condition that affects the muscle layer in the small and medium sized arteries that take blood from the heart to the rest of the body. This can cause the arteries to narrow, bulge, twist or tear, affecting the blood flow to the organs. FMD can affect any artery in the body but is most common in those that supply blood to the kidneys (renal arteries) and brain (carotid arteries).
FMD does not always cause any symptoms, so it is hard to tell how many people are affected. It could be as many as 1 in 250 people, although the majority will not need any treatment. Around 9 in 10 people with FMD are women, usually aged 25 to 50.
What are the signs and symptoms of FMD?
Many people with FMD do not have any symptoms. For those who do, symptoms depend on which arteries are affected. If the kidney arteries are affected, the main symptoms usually include high blood pressure and headaches.
If the neck or brain arteries are affected, the main symptoms can include a whooshing sound in the ears (pulsatile tinnitus) or migraines.
Other symptoms may present suddenly and can include:
- weakness or numbness in the face
- slurred speech
- a new or unusually severe headache or sudden neck pain
- severe abdominal pain, particularly after eating
Most people with FMD do not develop chronic kidney disease (CKD). However CKD can occur if high blood pressure is not managed or if there is a major tear or blockage of a kidney artery.
What causes FMD?
The exact cause of FMD is not yet known. It is more common in women, but no clear link has yet been found to female hormones or medications like the oral contraceptive pill or hormone replacement therapy (HRT).
No single gene has been identified to cause FMD, which is likely to be due to a combination of several genetic and environmental factors. Research in this area is ongoing.
Smoking has been linked to a more aggressive form of FMD, although the reason for this is not yet known.
How is FMD diagnosed?
As FMD often does not cause any symptoms, it may only be picked up when having a test for another condition. For example, it is found in around 1 in 50 people who put themselves forward to be living kidney donors.
FMD is diagnosed by a scan of the blood vessels (vascular imaging). There are several different ways in which this can be done:
- Contrast-enhanced CT angiography (CTA) – a non-invasive special X-ray scan that uses a harmless contrast dye that is injected into the veins to create detailed, 3D images of the blood vessels.
- Magnetic Resonance Angiogram (MRA) – a non-invasive scan that uses magnetic fields and radio waves to create detailed 3D images of the blood vessels.
- Duplex ultrasound – a non-invasive ultrasound scan of the blood vessels to give information about the blood flow. This test may be used alongside others as it does not give enough information by itself to guide treatment decisions.
- Intra-arterial Catheter angiography (IA) – an invasive procedure where a doctor inserts a thin, flexible tube into a blood vessel (usually through the groin or wrist), guides it to the area being examined, and injects a special dye so that the blood vessels show up clearly on X-ray images.
A ‘brain to pelvis’ scan is recommended
Does FMD affect other parts of the body?
FMD can affect other parts of the body, depending on which arteries are involved.
If it affects the arteries in the neck, it can cause problems ranging from face and neck pain to vision problems and an increased risk of stroke.
Does FMD run in families?
Fewer than 1 in 25 people with FMD also have a family member with the condition. A genetic basis has not yet been fully identified.
How is FMD treated?
There is currently no direct cure for FMD but treatment is very effective for the majority of people and focuses on preventing complications and controlling symptoms.
Treatment can include:
- Blood pressure medication
- Blood thinners such as aspirin
- Avowing certain other medications such as tryptans (migraine medicines) and quinolones (a type of antibiotic)
- A minimally invasive procedure called an angioplasty which uses a small balloon to open narrowed arteries and improve the blood flow. A repeat procedure may be needed if the blood pressure remains high.
In rare case, more invasive surgical procedures may be needed, especially if symptoms develop suddenly or if an angioplasty cannot be performed.
FMD is more common and more serious in people who smoke so help to stop smoking will be offered if it is needed.
Regular monitoring and imaging are needed but FMD rarely progresses and kidney failure is unlikely to develop.
Where can I get more information or support about FMD?
For more information on FMD, including its diagnosis, symptoms and treatment, visit the Fibromuscular Dysplasia Society of UK & Ireland’s Facebook group.
The national FMD clinic is run from Salford Royal Hospital as part of the Greater Manchester Northern Care Alliance. You can participate in research studies if you have been reviewed by the multi-professional team who run the clinic. There are also several recruiting centres to the UK FMD study. Contact your renal centre to see if they are participating.
The website of the Fibromuscular Dysplasia Society of America has patient information, support resources and research opportunities. Please be aware that this is a US site so some of the information may not be applicable for UK patients.
Publication date: 09/2026
Review date: 09/2029