High blood pressure was long considered a health problem of middle age, but rates are increasing in children and adolescents, with doctors reporting a surge in strokes among people of working age.
What is hypertension?
Hypertension is the medical name for high blood pressure. It arises when blood pressure in the arteries, the vessels that carry blood from the heart to the brain and around the body, is consistently above a healthy level. It is often called a silent killer because it causes damage throughout the body without producing obvious symptoms.
How is it diagnosed?
Blood pressure is usually measured with a blood pressure monitor, which wraps an inflatable cuff around the arm. The measurement records two numbers, in units of mm Hg (mercury), and displays them as the higher number over the lower. The higher number, the systolic pressure, is the pressure when the heart contracts to push blood around the body. The lower number, the diastolic pressure, is when the heart relaxes between beats.
Countries have different thresholds for diagnosing high blood pressure. In the UK, the healthy range for adults is 90/60 to 119/79. Slightly raised blood pressure is 120/80 to 139/89, and high blood pressure is from 140/90 upwards. In the US, a reading between 130/80 to 139/89 is called stage 1 hypertension, with stage 2 hypertension at 140/90 and over.
It is not as straightforward in children. Blood pressure changes throughout childhood relative to age and height, so there is no hard and fast threshold. Instead, doctors diagnose hypertension when blood pressure readings are in the top 5% of those for children of the same age, height and sex.
Who is at risk?
High blood pressure is common, especially among older people. About a third of UK adults and nearly half in the US have hypertension. Age is a major factor because arteries naturally stiffen and thicken with age. Genetics also matters, so family history is important. People from Black African, Black Caribbean or South Asian ethnic backgrounds are more at risk.
Lifestyle factors contribute, too: having an unhealthy diet, particularly one high in salt; being overweight or obese, a lack of exercise; smoking; drinking too much alcohol; and stress over a long period can all raise blood pressure.
What about children?
In very young children, high blood pressure is caused by other medical conditions such as heart problems, kidney disease, genetic or hormonal disorders. For this reason it is called secondary hypertension. But since the 1990s, rates of high blood pressure in children and adolescents have increased more than fourfold to 6% as poor diet, physical inactivity, and being overweight or obese take their toll and add to case numbers.
Why is hypertension harmful?
High blood pressure can steadily damage the body for years before people experience symptoms. The excess pressure can cause aneurysms, or bulges, in weak arteries, which can be fatal if they burst. The strain on the heart can lead to heart failure. The pressure also damages the smooth inner lining of arteries, leading to inflammation and plaques that make arteries stiffer and narrower. This can limit blood flow to the heart causing angina, irregular heart rhythms and heart attacks.
The kidneys are particularly vulnerable, with damaged blood vessels preventing the organs from filtering waste from the blood, which can leave people needing dialysis or a kidney transplant. The eyes are also at risk because of the tiny blood vessels in them, with damage causing bleeding, blurred vision and blindness.
Blocked or narrowed arteries can restrict blood flow to the brain causing vascular dementia and mini-strokes, while clots or bleeds caused by hypertension can result in major strokes.
High blood pressure can damage children’s organs, including the heart, kidneys and eyes, making it essential to diagnose and treat early.
What helps to reduce blood pressure?
Beyond blood pressure-reducing medicines, lifestyle changes can help. A healthy diet is crucial, with plenty of fresh fruit and vegetables, low fat dairy, and minimal salt. Minimise or avoid sugar-sweetened drinks, do not drink too much alcohol or smoke. Keeping a healthy weight is vital. Aim for an hour or more of moderate to vigorous exercise every day and limit sedentary activities, such as watching TV or playing on a computer, to less than two hours a day.
