Prehypertension: Does it really matter?
As doctors took blood pressure readings on millions of people over the
years, it became clear that hypertension is a major threat to health,
increasing the risk of stroke, heart attack, congestive heart failure,
kidney failure, and visual loss. And as data accumulated, it also became
clear that there is no bright line between a healthy blood pressure and
a harmful one; in general, the lower the pressure, the better.
Nevertheless, doctors need a target for blood pressure, and patients
also need a goal. Those goals changed in 2003, bringing the threshold
for a normal blood pressure reading lower than ever before, at 120/80
millimeters of mercury (mm Hg), and it also established a new diagnostic
category of “prehypertension” (see table).
Classification of blood
pressure for people 18 years or older
Stage 1 hypertension
Stage 2 hypertension
Systolic blood pressure
(BP) is the number recorded when the heart is pumping blood into
the arteries; diastolic BP is the number recorded while the heart
is refilling with blood between beats. All units are in mm Hg.
The revised standards provide simple guidelines for interpreting blood
pressure readings, but each reading generates two numbers. What if your
systolic and diastolic readings contradict each other? To determine your
classification, use the number that puts you in the higher group. For
example, if your reading is 114/84, you have prehypertension.
Each person has two arms; pressure readings often differ between them,
sometimes by 10 mm Hg or more. Which arm should you use to determine
your classification? It’s not a question of right vs. left but
of right vs. wrong: Use the arm with the higher reading.
Blood pressure readings can vary from time to time. Should you worry
about your peaks or take comfort from your valleys? Classification depends
on your usual or average blood pressure rather than
occasional extremes. For most people, a careful reading during an annual
checkup will suffice. But people with prehypertension or hypertension
should have their readings checked more often to get a true picture.
A new diagnosis
Prehypertension is not an illness — but it is an important warning
that illness lies ahead. Prehypertension increases the risk of developing
hypertension, a major illness indeed.
Prehypertension increases the risk of heart disease. According to a
2005 analysis by the Framingham Heart Study, men with prehypertension
are 3.5 times more likely to suffer heart attacks than those with normal
blood pressures. Surprisingly, although high blood pressure is a major
cause of strokes, prehypertension did not appear to increase the risk
What to do?
First, know your blood pressure. That means having it measured by a
health care professional or measuring it yourself with a high-quality
home blood pressure machine. Don’t count on headaches, nosebleeds,
a red face, or mental stress to warn you that your pressure is too high — none
of these traditional signs is reliable. Instead, have your pressure measured
with every check-up; once a year is ideal.
Second, find out if you have other cardiovascular risk factors such
as abnormal cholesterol levels, diabetes, a sedentary lifestyle, obesity,
tobacco abuse, and mental stress.
For most prehypertensives, treatment should depend on lifestyle changes,
not medications. Here’s what to do:
Diet. The Dietary Approaches to Stop Hypertension,
or DASH, program is best. It involves a reduction in dietary sodium to
2,300 mg a day or less; 1,500 mg a day is the tough new goal for people
with hypertension and for everyone who is middle-aged or older. The DASH
diet also calls for a low consumption of animal fat and processed foods.
Exercise. As little as 30 minutes of moderate
exercise, such as brisk walking, will produce enormous benefits — as
long as you do it nearly every day.
Weight control. One of the most important
ways to reduce blood pressure, it’s also one of the hardest to
achieve. A calorie-restricted healthful diet, such as DASH, plus regular
exercise can help.
Moderate alcohol use. Small amounts of alcohol
won’t raise your pressure, but heavier drinking will. If you choose
to drink, limit yourself to two drinks per day, counting 5 ounces of
wine, 12 ounces of beer, or 1½ ounces of spirits as one drink.
Low-dose alcohol appears to reduce the risk of heart disease and stroke,
but no one should take up drinking strictly for its medical benefits.
Stress control. It’s harder to quantify
than the other lifestyle goals, but a number of studies suggest that
meditation and other relaxation techniques can help lower blood pressure.
Healthful living will prevent many cases of high blood pressure, and
it can replace or reduce medications for many hypertensives.
Medication. Should you take medication for
prehypertension? It’s an important question, but doctors don’t
know the answer. They do know that readings below 120/80 are best, but
they don’t know if medication should be used to reach that low
goal. More study is needed. But even now, patients with diabetes, chronic
kidney disease, and heart disease should take medicine if that’s
what’s needed to bring their pressures below 130/80.
April 2007 update
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