Blood pressure is the pressure placed on the inner walls of our blood vessels (veins, arteries and capillaries) as the heart pushes blood through the body.
When the heart beats, the blood pressure is called systolic blood pressure. When the heart relaxes between beats, the resulting blood pressure is called diastolic blood pressure.
Blood pressure is measured in units of pressure called millimetres of mercury (mmHg). For example, a measurement of 105/55 mmHg means the systolic blood pressure is 105 mmHg and the diastolic blood pressure is 55 mmHg. It is reported as 105 over 55 mmHg.
Systolic and diastolic blood pressures increase gradually from infancy to adulthood.
What is hypertension?
Hypertension is another name for high blood pressure.
Normal values for blood pressure depend on a child's age, gender and height. Hypertension occurs when a child's blood pressure is recorded as higher than that of 95 percent of children of the same age, gender and height for children 1–12 years old or >130/80 mmHg for children more than 13 years old. Another category of high blood pressure, "elevated blood pressure", occurs when a child's blood pressure is higher than that of 90 percent of children of the same age, gender and height or >120/80 mmHg.
Types of hypertension in children
There are two main types of hypertension in children:
- primary hypertension
- secondary hypertension.
Primary hypertension
Primary hypertension is the most common type of high blood pressure in older children and teenagers. It is more likely to occur in those who are overweight or obese or have a family history of high blood pressure or heart disease. It is called primary hypertension because no cause has been identified for the high blood pressure. It should only be diagnosed after other causes are ruled out.
Secondary hypertension
Secondary hypertension is more common in children than in teenagers and adults. It can be caused by one or more of the following:
- kidney disease
- hormone problems (for example, endocrine disease)
- medications or other drugs
- neurological conditions (conditions that affect the brain and central nervous system)
- heart or blood vessel problems
Symptoms of hypertension
A child is more likely to have hypertension symptoms with secondary hypertension. Symptoms include:
- increasing irritability or other behaviour changes
- blurred vision
- headaches
- shortness of breath
- puffy hands or feet
Very severe hypertension can cause seizures.
How hypertension is treated
Hypertension is treated differently depending on its cause. Both primary and secondary hypertension may be treated with diet, exercise and, sometimes, medication. Children with secondary hypertension may also receive treatment for the medical condition that is causing the high blood pressure.
Diet and exercise
If your child is overweight or obese, losing weight may help lower their blood pressure. Maintaining normal weight gain should also lead to less hypertension in adulthood.
- Try to give your child a diet that is low in salt and has lots of vegetables, fresh fruit, fibre and low-fat dairy.
- Limit your child's portion sizes, serve them fewer sugary drinks such as juice and pop and have them eat regular meals, including a healthy breakfast.
- Encourage your child to do regular physical activity (30 to 60 minutes of moderate physical activity on most days) and limit screen time to less than two hours a day.
Anti-hypertensive medication
If your child needs to take medication to control their high blood pressure, follow your doctor's instructions carefully both for taking the medication and for monitoring any side effects.
When to have your child's blood pressure checked
All children over three years of age should have their blood pressure measured at least once a year during routine visits to their primary health-care provider. If your health-care provider has not measured your child's blood pressure starting at age three, ask them to measure it at your child's next appointment.
Blood pressure measurements may be recommended for children under age three if they are at a higher risk for high blood pressure, for example if they have kidney or heart disease.
Getting an accurate blood pressure measurement
Doctors normally measure the blood pressure in an artery using an inflatable cuff wrapped around an arm or a leg. It is important for blood pressure to be measured on a calm child with the correct-sized cuff. Blood pressure measurements can be incorrect if they are taken with a poorly fitting cuff or when a child is frightened or crying.
Long-term consequences of hypertension
Children and teenagers with hypertension are at risk of damage to many different parts of the body, including the heart, eyes and kidneys. Children with hypertension who are also overweight and obese may also have difficulties sleeping or have trouble using the body's sugars, a condition known as pre-diabetes.
When to see a doctor for hypertension
Make an appointment with your child's doctor if your child:
- has high blood pressure when being monitored at home or by another health-care professional
- is taking anti-hypertensive medications and needs a new prescription
- has a persistent headache or one that wakes them from sleep or occurs with vomiting
- becomes short of breath
- becomes puffy or swollen in their hands, feet or face
Go to your nearest Emergency Department or call 911 if your child:
- becomes very lethargic or cannot be roused
- has a seizure
- suddenly becomes weak in one arm or leg or on one side of the body
- becomes very short of breath and is breathing very quickly
- has a very severe, persistent headache