The definition of high blood pressure is changing. As a result of new understandings into the health hazards of even a slightly raised blood pressure, the diagnosis of prehypertension, or high normal blood pressure, was recently scrapped in the United States. In its place, new definitions for ‘elevated blood pressure’ and Stage 1 hypertension have been introduced.
The term ‘prehypertension’ is still in use within Europe – at least for now – but is likely to follow the US lead in the near future.
Prehypertension was diagnosed when your blood pressure numbers were consistently above the level of 120/80 mmHg but below 140/90 mmHg – the level previously needed to diagnose high blood pressure, or hypertension.
In the US, however, the blood pressure levels previously referred to as prehypertension have now been divided into two new categories of:
- elevated BP if your upper reading (systolic pressure) is between 120 and 129 mmHg but your lower reading (diastolic pressure) remains less than 80 mmHg
- stage 1 hypertension if your systolic pressure is between 130 to 139 mmHg OR your diastolic pressure is between 80 to 89 mmHg.
Prehypertension, or high normal blood pressure, was defined as having a blood pressure that is consistently between 120/80 mmHg and 139/89 mmHg. Only one of your blood pressure readings needs to be in this range to diagnose prehypertension, so if your systolic blood pressure (upper number) is between 120 mmHg and 139 mmHg, or if your diastolic blood pressure (lower number) is between 80 mmHg and 89 mmHg you have prehypertension (or high normal blood pressure).
You can check how your blood pressure ranks using the following charts. The one on the left shows the older classification, which includes the term ‘prehypertension’ while the chart on the right shows the new US classification so you can see how they differ.
Find your systolic pressure reading (top number) on the left of the charts, and your diastolic pressure reading (bottom number) across the bottom of the charts. Where these lines meet on the chart will show if either reading is low, normal or within the pre-hypertension (old), elevated (new) or hypertension ranges.
If your systolic and diastolic blood pressures fall into different categories the higher classification is used.
You can print off these charts using the links at the bottom of the page.
Your blood pressure will be checked several times to see if it comes back down into the normal range.
How common is prehypertension?
Prehypertension (now elevated or stage 1 hypertension) is at least as common as hypertension, with at least a third of adults affected. The insidious rise in blood pressure is so common that some researchers have described it as the prehypertension tsunami.
Why is prehypertension bad?
There is growing recognition that people whose blood pressure falls within the prehypertension (now the elevated or stage 1 hypertension) range have an increased risk of developing circulatory complications compared to those whose blood pressure is below 120/80 mmHg. In the long-term, elevated blood pressure doubles the risk of a heart attack or stroke.
One study followed 204 ‘healthy’ people with prehypertension for up to 20 years, or until their first cardiovascular event occurred. More than two out of five went on to develop hypertension that needed treatment.
Around one in 8 experienced a circulatory event such as needing a coronary artery revascularisation, fatal or non-fatal heart attack, heart failure, fatal or non-fatal stroke, or developed an abdominal aortic aneurysm.
One third of those who developed these serious complications were within the prehypertension range at the time. This is why the term is being scrapped in favour of ‘elevated blood pressure’ and stage 1 hypertension.
Prehypertension and stroke
Worldwide, at least 54% of strokes are attributable to high blood pressure.
People with prehypertension also have a higher risk of stroke than if their blood pressure were below 120/80 mmHg.
The results from 19 studies, involving 762,393 people, show that, after adjusting for all other cardiovascular risk factors, having prehypertension is associated with a 66% increased risk for stroke, compared with having an optimal blood pressure of less than 120/80 mm Hg.
If your blood pressure is in the LOW end of the prehypertension range (systolic 120 mmHg to 129 mmHg, and/or diastolic 80 mmHg to 84 mmHg) you have a 44% increased risk of stroke compared with having a normal blood pressure.
If your blood pressure is in the HIGH end of the prehypertension range (systolic 130 mmHg to 139 mmHg, and/or diastolic 85 mmHg to 89 mmHg) you have a 95% increased risk of stroke compared with having a normal blood pressure.
Prehypertension and kidney disease
Having a higher than optimal blood pressure damages the tiny filtering units within the kidneys. Research involving 261,264 people aged from 20 to 89 years, who were followed for up to 11 years found that people with prehypertension were 28% more likely to develop chronic kidney disease than those with optimal blood pressure.
If you were previously told you had prehypertension, or high normal blood pressure, your doctor may now rediagnose you as having elevated blood pressure or stage 1 hypertension. The treatment remains the same with advice to make diet and lifestyle changes which can bring your blood pressure down into the normal range. Drug treatment is not prescribed unless your blood pressure creeps higher or you have a 10% or greater long-term risk of developing a heart attack or stroke.
Having a diagnosis of prehypertension, elevated blood pressure or hypertension is an important health crossroads. It shows that your blood pressure is increasing due to a combination of factors such as your age, diet, lifestyle, weight, and the genes you have inherited, which all contribute to the underlying causes.
Making a few simple changes will help bring your blood pressure down without the need for medication.
That’s what this blood pressure site is all about.
- Cut back on salt and avoid monosodium glutamate
- Follow a DASH (Dietary Approaches to Stop Hypertension) Diet
- If you smoke, it is important to quit – cigarettes damage artery linings and constrict arteries
- Take regular exercise (eg walking, cycling, swimming, gardening) for at least 30 – 60 minutes, five times a week – and preferably every day
- Lose some excess weight – shedding just half a stone (3kg) can bring your readings down
- Avoid excess alcohol
- Avoid white potatoes
- Drink cocoa, beet juice and cherry juice
- Check if you are sensitive to the effects of caffeine
- Use breathing exercises
- Use the RESPeRATE device
- Avoid stress and take time out for relaxation exercises or meditation
- Practice Shinrin-yoku forest bathing
- If you have diabetes, it is important to maintain good control – raised glucose levels hasten hardening of the arteries and hypertension.
- Eat more flaxseed, black cumin seed, yogurt, grano padano cheese and oily fish
- Consider herbal remedies such as chamomile tea, Hibiscus tea, aged garlic, Reishi, Rhodiola or Valerian
- Consider supplements such as calcium, magnesium, fish oil, coenzyme Q10, L-arginine, potassium, vitamin C, vitamin D, vitamin E or lycopene
- Consider natural treatments such as reflexology, floatation therapy, music therapy and aromatherapy.
Monitor your blood pressure
When you have prehypertension, it is important to monitor your blood pressure regularly, to ensure your diet and lifestyle changes are bringing it down, and that you are not creeping up into the hypertension range.
Self-monitoring is key to help stop your prehypertension progressing to hypertension.
Click here for advice on choosing a blood pressure monitor to use at home.
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