Blood pressure (or BP) is the pressure of blood inside your arteries. The higher your blood pressure, the harder your heart needs to work to pump blood around your body.

Blood pressure is measured in millimetres of mercury (mmHg), and is written as two numbers, such as 130/80 mmHg :

• The first number is your ‘systolic blood pressure’. This is measured as your heart beats and is the highest pressure your blood reaches.
• The second number is your ‘diastolic blood pressure’. This is measured when your heart relaxes between beats and is the lowest pressure.

So, if your systolic blood pressure is 130 mmHg and your diastolic blood pressure is 80 mmHg, your blood pressure is said to be ‘130 over 80’, written as 130/80 mmHg.

Your doctor will diagnose you with high blood pressure (hypertension) if your blood pressure is:

• 140/90 mmHg or higher when measured more than once in the clinic
• 135/85 mmHg or higher when measured throughout the day.

Diagnosing high blood pressure in children is done differently. An appropriately sized blood pressure cuff is used. Children are diagnosed with high blood pressure if their systolic or diastolic blood pressure is high compared with the usual range for their age, height and sex.

Having high blood pressure means that your heart has to work harder to pump blood around your body. It increases your risk of having serious cardiovascular problems, including a heart attack, heart failure, bleed on the brain (intracranial haemorrhage) or stroke.

If you have an enlarged blood vessel in your brain (called a brain aneurysm), having high blood pressure could slightly increase the risk of it bursting. You can learn more about aneurysms on our website.

The risk of having a cardiovascular problem differs between people, depending on factors including :

• blood pressure
• age
• sex
• smoking
• cholesterol level
• other conditions, e.g. diabetes
• the condition of their heart and arteries

The good news is that your risk of cardiovascular disease can be reduced with treatment to lower your blood pressure. Treatment is usually quite straight forward. If you have high blood pressure, your doctor can recommend lifestyle changes and medications to lower your blood pressure and risk (see below).

If your blood pressure is extremely high, it could affect your ability to drive (it can alter your vision). If it’s above 180/100 mmHg, you should not drive until a doctor confirms it has reduced and is well controlled. Speak to the DVLA for advice.

Most people with high blood pressure have no symptoms. It’s spotted and diagnosed through blood pressure monitoring. This is why periodic blood pressure monitoring is recommended for people with ADPKD.

Most people with ADPKD have their blood pressure measured when they go to their kidney clinic for check-ups. This is usually at least once a year. Experts recommend that children with ADPKD (or at risk of ADPKD) have their blood pressure monitored every 2 years from age 5 years.

Adults who haven’t been diagnosed with ADPKD but who are at risk can choose to have their blood pressure checked. This is normally done at least once every 3 years.

Your doctor will use a blood pressure monitor (a small machine with an arm cuff) to measure your blood pressure. If these readings show it is high, you’ll be offered blood pressure monitoring over 24 hours while you go about your normal life. This is called ambulatory blood pressure monitoring. You’ll wear a monitor strapped round your waist and a cuff wrapped around your upper arm. The cuff inflates and deflates automatically throughout 24 hours to take recordings of your blood pressure. Ambulatory blood pressure monitoring is used to confirm that you have high blood pressure.

It’s normal for our blood pressure to lower while we sleep. In some people with ADPKD this doesn’t happen, even if their daytime blood pressure is normal. Ambulatory blood pressure monitoring can be especially useful for spotting night-time increased blood pressure.

If this type of monitoring is not suitable for you, your doctor might offer to lend you a blood pressure machine so you can take your own readings throughout the day. This is called home blood pressure monitoring.

If you’re found to have high blood pressure, your doctor may offer a urine test, blood test, eye test and electrocardiogram (ECG) of your heart. This is to check for other problems that high blood pressure can cause.

Your doctor will also calculate your risk of having cardiovascular problems and explain this to you.

For the general public and adults with ADPKD, the recommended or ‘target’ blood pressure is generally 140/90 mmHg or less. Some experts recommend a lower target than this (e.g. 130/80 mmHg for those with kidney function under 60%, or <110/75 mmHg for those with kidney function over 60%). Your doctor will recommend the best target for you.

Blood pressure targets in children are based on what is normal for their age, sex and height.

Your doctor will suggest lifestyle changes and medications to bring your blood pressure below this target.

Taking the steps below can help to lower your blood pressure and reduce your risk of having a cardiovascular problem :

• Lose any excess weight (the recommended body mass index for most adults is 18.5 to 24.9 weight (kg) / [height (m)]²).
• Exercise regularly.
• Eat a healthy, balanced diet.
• Do not add salt to your diet and only eat up to 5-6 g of salt a day (check food labels, as packaged food often contains added salt).
• If you drink a lot of caffeine (e.g. coffee, tea, cola, energy drinks), cut this down.
• Give up smoking.
• If you drink a lot of alcohol, cut this down (general guidelines now suggest 14 units or less per week whether you’re a man or woman).

You’ll find more detailed information and tips on a healthy diet and lifestyle on our website.

If you have high blood pressure and ADPKD, your doctor should discuss options for medication with you. Medications to reduce blood pressure are known as antihypertensive drugs. For people with ADPKD, one medication will probably be enough to control blood pressure. However, some people are advised to take more than one.

Your doctor will probably recommend an angiotensin-converting enzyme (ACE) inhibitor or angiotensin-II receptor blocker (ARB), unless there is a reason you cannot take these.

• Examples of ACE inhibitors are lisinopril, perindopril and ramipril
• Examples of ARBs are candesartan, losartan and valsartan.

A common side effect of these medicines is that your blood pressure may become too low. This is called hypotension and can make you feel dizzy or tired. Some people get a persistent dry cough with ACE inhibitors. Other side effects are less common — ask your doctor for more information to help you decide which medication might be best for you.

Other medicines sometimes used to reduce blood pressure are calcium channel blockers and diuretics. If your ACE inhibitor or ARB is not controlling your blood pressure sufficiently, your doctor may suggest adding one of these medications.

If you have any side effects, talk to your doctor. There are many medications to lower blood pressure, so work together with your doctor to find the right one for you.

These medicines work by reducing the amount or action of a hormone in your body called angiotensin II. This hormone can increase blood pressure. By reducing angiotensin II signalling, ACE inhibitors and ARBs reduce your blood pressure.

To keep your blood pressure at a healthy level, you’ll need to continue your healthy lifestyle and your prescribed medication. You’ll have annual blood pressure checks. If your blood pressure is not well controlled, your doctor can recommend different or additional medications for you.

Some people like to check their blood pressure themselves. While you should not rely on this instead of having checks with your doctor, it can be helpful to put your mind at ease. Your kidney specialist or GP might suggest home monitoring, and some chemists offer free blood pressure checks. To find your nearest chemist offering this service, go to bloodpressureuk.org Alternatively, you could consider buying your own approved blood pressure monitor.

ADPKD can increase blood pressure in two main ways: 1) by altering the lining of your blood vessels, and 2) by activating hormones that control blood pressure.

The faulty genes that cause ADPKD (PKD1 and PKD2) are not only important for your kidneys: they’re also found in the lining of your blood vessels. When these genes don’t work correctly, it can interfere with the way that the vessels tighten and relax. In people with ADPKD, blood vessels tend to be tighter and narrower than usual. Narrower vessels mean the blood has less room to flow, increasing blood pressure. You could think of it like a motorway where a lane has been closed — the traffic becomes busier as it fights for space.

ADPKD can also activate hormones that control blood pressure (e.g. angiotensin II). There are a number of reasons why these hormones can be activated. For example, kidney cysts can squash tiny vessels in the kidney, which makes it harder for blood to flow through them. This can lead to hormones levels rising as the body tries to get more blood to the area.

High blood pressure tends to worsen as kidney cysts grow and the kidneys enlarge.

People whose ADPKD has progressed quite a lot are at increased risk of having additional cardiovascular problems, especially if their blood pressure isn’t controlled. These include:

• hardening and narrowing of the arteries (known as atherosclerosis)
• thickening of the walls of the left side of the heart due to it having to work harder (known as left ventricular hypertrophy)
• a swollen blood vessel in the brain (brain aneurysm)

These conditions increase your chance of having a potentially fatal problem such as abnormal heart rhythm, a heart attack or stroke , so it’s important they’re monitored and treated.

If you have a high risk of having a cardiovascular problem, your doctor might recommend additional medications. These include:

• antiplatelet drugs (e.g. aspirin or clopidogrel) to reduce your risk of a blood clot
• lipid-lowering drugs (statins) to reduce your cholesterol

Additional treatments to lower cardiovascular risk are being tested in clinical trials.

Your doctor will be able to explain whether additional medications might be helpful for you and why.

• ADPKD and aneurysms
• Diet and lifestyle
• ADPKD progression

• For more information and advice on blood pressure, including information on blood pressure monitors, go to the Blood Pressure Association website.
• For more information on strokes and heart attacks, go to the British Heart Foundation website.
• To calculate your body mass index and get tips on losing weight, go to the NHS website.
• You can read the latest guidelines on high blood pressure (hypertension) at the NICE website. There is a summary for patients, as well as more detailed information aimed at doctors.

Find your nearest chemist offering free blood pressure checks at bloodpressureuk.org.