If you've had a high blood pressure reading, or you've been diagnosed with high blood pressure, there are a number of tests you might need.
These tests and checks may help to get a better idea of your blood pressure and your overll health. They can help to show what your blood pressure is like on a day to day basis, if high blood pressure has had any effect on your body, and what might be causing it.
Tests to measure your blood pressure
If you have a high blood pressure reading, your doctor might want you to have more readings to find out if you have high blood pressure over a longer period. There are a number of ways to get a better idea of your blood pressure:
- having your blood pressure checked a number of times at your doctor’s surgery over a few weeks or months
- measuring your blood pressure at home using a home monitor
- 24-hour ambulatory home blood pressure monitoring (ABPM) – where you wear a small blood pressure monitor around your waist that takes regular readings for 24 hours.
If you are diagnosed with high blood pressure, your doctor will advise you to make healthy changes to your lifestyle, and might talk to you about medications to lower your blood pressure. You might also have some other tests to get a better idea of your overall health, see below.
Measuring your blood pressure at home using a home monitor
Measuring your blood pressure at home using a home blood pressure monitor can be a really useful way of seeing what your blood pressure is like in your daily life. You can take measurements at different times of day, and when you’re comfortable at home, away from the stress of being in a clinic. It can also be used to see if any medications or lifestyle changes are working.
You might be able to borrow a home monitor from the GP surgery, or you might need to buy one yourself.
Your doctor or nurse will advise you on how to use a monitor, how often you should take readings, and how long for. You will probably be asked to take two to three readings in the morning and again in the evening, every day for a week. These tips for measuring your blood pressure at home will help.
24-hour ambulatory home blood pressure monitoring
Ambulatory Blood Pressure Monitoring (ABPM) is where you wear a small blood pressure monitor around your waist to measure your blood pressure over the course of a normal day. It’s more accurate than a one-off measurement in clinic, where your blood pressure could be raised due to the stress of being in clinic (white coat syndrome).
The monitor will be fitted either in hospital or at your GP surgery. It will be attached to a belt which you wear around your waist, and is connected to a cuff around your arm. It takes readings every 15-30 minutes while you go about your daily life, and every hour or two while you sleep. It works in much the same way a regular monitor, inflating the cuff and taking readings as it deflates.
This type of monitoring can also be used once you are taking medications, if you need them, to see how well they’re working.
Getting the most out of 24-hour monitoring
The following will help your doctor get a good idea of what your blood pressure is really like, your doctor or nurse will also give you any instructions you need.
- Choose a normal day. The idea is to measure your blood pressure over a normal day, so you don’t need to do anything differently. The only exceptions are you should avoid getting the monitor wet, driving and vigorous exercise.
- Avoid swimming or having a bath or shower. The monitor will be damaged if it gets wet. If you need to have a bath or shower, remove the monitor and put it on again as it was before.
- Avoid driving. If you need to drive, switch the monitor off before starting your journey and back on when you arrive.
- Avoid vigorous exercise. Limit exercise to brisk walking so you don’t have lots of high readings.
- Wear a loose top. This will be more comfortable and allow the cuff to inflate and deflate.
- Don’t let the tube get twisted. The monitor won’t work properly if the tube connecting it to your arm cuff is bent, twisted or has a kink in it.
- Sit down when you hear the beep. The monitor will beep before it takes a reading. When you hear the beep, sit down if possible and keep still and quiet while the reading is taken. Support your arm on a table or the back of a chair, with the cuff at the same level as your heart. If you’re standing, support the arm being measured with your other arm.
- Keep a diary. You’ll be asked to keep a record of what you were doing each time you heard a beep, what time you got up and went to bed, and what time you took ay medications you’re taking.
- Speak to your doctor or nurse if you have any trouble with it. If you find the monitor distracting or uncomfortable, let your doctor or nurse know because this could affect your reading. If you experience any pain, take off the monitor.
Further tests on your overall health
If you have had a high reading or you have been diagnosed with high blood pressure, your doctor should try to find out more about what’s causing your high blood pressure and how it’s affecting your body, as well as any other health problems you may have. This is so they can find the right treatment.
They will ask you questions about your diet and lifestyle, any health problems you have or have had in the past, and any illnesses in your family. For example, high blood pressure, heart disease and stroke. You may also have some other tests, including:
Blood tests and high blood pressure
A blood test is a quick and simple way to check for signs of health problems. For example:
- high cholesterol – which can clog up your arteries and lead to heart disease
- certain proteins – which can be a sign of kidney problems
- blood sugar – which can be a sign of diabetes or pre-diabetes
- certain hormones – which can show if you have hormone disorders such as a disease of the thyroid or adrenal glands
To do a blood test, your nurse will use a syringe and a small needle to take a small amount of blood. The blood sample will be sent to the hospital for analysis and the results will usually come back within a few days.
If you only need your blood sugar measured, you might have a finger prick test instead, where only a few drops of blood are taken.
Urine tests and high blood pressure
Urine tests can give a lot of information about your body. There are two types of urine test, a simple test where you give one sample in a small container, and a 24-hour test where you collect all your urine over 24 hours. You will be given instructions on how to do this. Which type of test you need depends on how much information your doctor needs. Urine tests can pick up on:
- proteins – which can be a sign of kidney problems
- blood – small amounts of blood can be a sign of kidney or bladder problems
- sugar – which can be a sign of diabetes or pre-diabetes
- sodium (part of salt) – which shows how well your kidneys are working, and to monitor the side effects of any medications you’re taking
- signs of a rare cause of high blood pressure called phaeochromocytoma
Electrocardiogram (ECG) and high blood pressure
An ECG measures the rhythm of the heart and the electrical signals in the heart when it beats. Small sticky sensors on the skin on your chest, arms and legs are connected to a machine which creates a graph of your heart beat – creating the familiar wavy line – either on paper on a screen.
An ECG can show if your heart is working properly, and can detect problems, including:
- an irregular heartbeat, or if the heart is beating too slowly or quickly
- coronary heart disease, where cholesterol clogs up the arteries and the blood flow to the heart is restricted
- signs that you might have had a heart attack in the past
- the walls of the heart have become thickened.
An ECG is safe and painless and only takes a few minutes. You will either have the results there and then, or they might need to be analysed and you’ll have the results at your next appointment.
There are three main types of ECG, and the type you have will depend on what your doctor is looking for:
- Resting ECG. This shows how well the heart is working when you are lying down and relaxed.
- A stress or exercise ECG. This shows how your heart works when it’s having to work harder, while you’re exercising on an exercise bike or treadmill.
- An ambulatory or 24-hour ECG. This is where you wear the electrodes, connected to a small machine which you wear around your waist, for a day or two at home so your heart can be monitored for longer.
Echocardiogram and high blood pressure
An echocardiogram is a type of ultrasound scan which uses sound waves to give a moving image of the heart. It shows the structure of the heart, how well it’s working and if there are any signs of damage. For example, it can show if the walls of the heart have become thickened or enlarged, damage from a previous heart attack, and problems with the valves.
To have the scan, you will lay on a bed with some sticky electrodes placed on your skin. You will have some gel placed on your chest over your heart, and the person doing the scan will hold a probe against your chest to examine the heart from different angles. Images of your heart will appear on a screen.
This type of scan is called a transthoracic echocardiogram. There are other types of echocardiogram, and the type you have will depend on what your doctor is looking for.
- Transoesophageal echocardiogram. Where a tube with a probe on the end is passed down your oesophagus (food pipe) into your stomach. It gives a more detailed image of the heart.
- Stress echocardiogram. Where you have the scan during or just after exercising. Or you may be given an injection, which makes the heart work harder.
- A contrast echocardiogram. Where a harmless substance is injected into your blood stream and is detected by the scan to give a clearer image.
The scan takes up to an hour and is safe and painless. Your doctor might be able to discuss the results there and then, or the images might be sent off to be analysed and you’ll have the results at your next appointment.
Eye tests and high blood pressure
An eye test can pick up on any damage to the blood vessels in your eyes before it causes any problems.
Damage to the blood vessels in the eyes is also a sign of damage to blood vessels elsewhere in the body, for example in the kidneys. The eyes are the only place where the small blood vessels can be seen. In fact, many people discover they have high blood pressure after a routine eye test.
An eye test will sometimes be done by your GP, but more commonly by an eye specialist (ophthalmologist). They will give you eye drops to widen your pupils and give a better view of the back of your eye (the retina). They will then shine a light on the back of your eye and use magnifying lenses to look at the blood vessels.
Take some sunglasses to wear after your eye test, as the bright light can make your pupils wider for a few hours, letting more light in. It’s also a good idea to arrange transport home as your vision might be a bit blurry for a few hours.