Hypertension: tests and diagnosis

Diagnosing hypertension

The first tests are to obtain accurate blood pressure measurements. Because hypertension in children is rare, your child’s doctor will also do an examination of your child and arrange urine tests and blood tests. Some children will need further tests.

Measuring blood pressure

At hospital or GP clinic

Your child’s doctor or nurse measures your child’s blood pressure. An electronic or manual (worked by hand) instrument, which is the best type and size for your child, is used.

Measuring blood pressure in young children can be challenging especially if they are anxious or frightened. Your child’s doctor or nurse will take a few measurements when your child is relaxed. Your child may need to go back on three separate occasions for more measurements.

At home

Blood pressure can vary throughout the day, when we exercise and when we feel stress. Some children feel stress when they visit the doctor. If they feel stress and have higher blood pressure, and no other symptoms of hypertension, this is called white coat hypertension. Your doctor or nurse may ask a community nurse to measure your child’s blood pressure at home. Or, you may be asked to use a home electronic monitor to measure your child’s blood pressure at regular intervals during the day.

Ambulatory blood pressure monitoring

One of the best ways to assess a child suspected of hypertension is to use ambulatory blood pressure monitoring (ABPM). Your child may be fitted with a special electronic monitor that automatically measures blood pressure over a period of time, usually 24 hours.

This monitor will automatically measure your child’s blood pressure every half hour during the day, and every hour during the night while they are sleeping. Your child will need to keep their arm still during each measurement. ABPM gives a true picture of your child’s blood pressure when he or she is awake and asleep. It is normally only used for children aged 5 years or older.


Your doctor will talk to you or your child about his or her symptoms and any medicines that he or she takes, and do an examination of your child.

Urine tests

You or a nurse will collect some of your child’s urine in a small, clean container for a urine test. A dipstick is used – this is a strip with chemical pads that can change colour depending on what substances are in the urine. The urine sample may also be sent to a laboratory for more testing.

Blood tests

Blood tests may be taken to check kidney and thyroid hormone levels in your child’s blood. A small amount of blood will be taken from a vein with a needle and syringe.

If your child is diagnosed with hypertension, your doctor may arrange other tests.

Imaging test

These use special equipment to get images of the inside of the body. These scans should not cause any pain. Some scans require an injection using a needle or plastic tube – a local anaesthetic, a spray or cream, can be put on the skin before the test to make the area numb.

  • Ultrasound scanlooks at look at the shape and size of the kidneys and other parts of the urinary system. A small handheld device is moved around your child’s skin and uses sound waves to create an image on a screen.
  • DMSA – shows whether there is any damage in the kidneys or other parts of the urinary system. A chemical that gives out a small amount of radiation is injected into one of your child’s blood vessels, and a special camera takes pictures.

Imaging tests used for hypertension

Electrocardiogram (ECG)

An electrocardiogram (ECG) checks whether the heart is working too hard, or if there any problems with the heartbeat. Small sticky patches are put on your child’s arms, legs and chest, and connected to a machine.

Angiogram and angioplasty

If the arteries (blood vessels) that lead to the kidneys are too narrow, this means there is less blood flowing to the kidneys, which can lead to hypertension.

  • An angiogram is a type of imaging test that looks at these arteries in detail. A general anaesthetic (GA) is used to make your child go to sleep so he or she does not feel pain anywhere in his body. The doctor makes a very small cut in the skin. He or she uses an ultrasound scanner as a guide, and inserts a needle through the cut into one of the large arteries in the body – usually one in the groin. A long thin tube called a catheter is passed through this artery until it reaches the artery leading to the kidney, and a special dye is placed through the catheter to flow to the kidney. X-ray images are taken.
  • An angioplasty is a treatment that stretches the artery. This lets blood flow more easily to the kidney, and so helps reduce blood pressure. A small balloon is placed through the catheter and when it gets to the narrowed section, it inflates. After the procedure, the catheter is drawn back and removed, and the opening in the skin heals in a few days.


Depending on the results of these tests, your doctor may refer your child to:

  • a paediatrician, a doctor who treats babies, children and young people, and may be in a hospital or a clinic
  • a paediatric nephrologist, a doctor in a paediatric renal unit (a specialised unit that treats babies, children and young people with kidney conditions) who specialises in treating babies, children and young people with kidney problems, and may need to confirm the diagnosis and advise on treatment.

Questions to ask the doctor or nurse

  • What other tests will my child need?
  • How do I help prepare my child for the tests?
  • Why does my child have hypertension?
  • How will you know if my child has an underlying condition? How can I get more information about that condition?

More information

  • Blood pressure

    Blood pressure (BP) is the force, or pressure, that makes the blood flow round the body. It is very important that your child’s blood pressure is in a healthy range. If it is too high or too low, your doctor will try to find out what is causing this.

  • Measuring blood pressure

    Information about how children's blood pressure is measured in clinics, surgeries or hospitals, and when you might be asked to measure blood pressure at home.

  • Blood pressure and your child’s health

    Understand more about children's blood pressure, how the kidneys control blood pressure to help make sure it is at a healthy level and how you can keep the whole family's blood pressure in a healthy range.