The Dangers of Prehypertension

It's Not High Blood Pressure, Yet, but You Still Need to Address It

Is your blood pressure creeping up? ... Not quite in the high blood pressure range, but not normal, either?
That's prehypertension. And though it's not high blood pressure -- yet -- it may not be as harmless as you thought.
Here's what you need to know about prehypertension, and why you need to nip it in the bud.
First, the numbers:

• Normal blood pressure is below 120/80.
• Prehypertension is blood pressure that ranges from 120-139 for the top number or 80-89 for the bottom number.
• High blood pressure (hypertension) is 140 or higher for the top number, or 90 or higher for the bottom number, or you are taking a blood pressure medication.

The top number is your systolic pressure, which is the force of blood against your arteries as your heart beats. The bottom number is diastolic pressure, which is the pressure on your arteries when your heart relaxes between beats.

Stroke Risk

Having prehypertension may make you more likely to have a stroke, especially in people younger than 65, a recent study shows.

"If you have prehypertension, and you're under 65, it really matters," says researcher and neurosciences professor Bruce Ovbiagele, MD, of the University of California, San Diego. "Most people who get to 65 already have hypertension."

Ovbiagele's team also found that stroke was more likely for people at the upper end of the prehypertensive range. But even if your blood pressure is not that high, it's wise to take action if your blood pressure is heading in the wrong direction.

"No matter what you consider your break point, any increase in blood pressure is generally a bad thing," says Richard Stein, MD, who directs the exercise, nutrition, and cardiovascular program at New York University's Center for Prevention of Cardiovascular Disease.

"It's causing the heart muscle to beat against a higher pressure, so [the heart] is becoming thicker," Stein says, adding that high blood pressure is also stressful for the kidneys.

Becoming More Common

More than a quarter of U.S. adults -- 28% -- have prehypertension, according to CDC estimates. About 20% of people who have prehypertension will go on to develop hypertension, Ovbiagele says. High blood pressure is the leading cause of stroke and also a major risk factor for heart disease and kidney damage.

Prehypertension and hypertension are on the rise. They've become more common as the U.S. becomes more obese and sedentary, Stein says. You're also more likely to get prehypertension if you have diabetes, high cholesterol, or a family history of high blood pressure, Stein says.

Prehypertension is a particular problem among African-Americans. Researchers have reported that African-Americans with prehypertension develop high blood pressure a year sooner than Caucasians. Although the reasons why are unclear, experts do know that "blood pressure is very difficult to control in African-Americans," Ovbiagele says.

Stealth Threat

Prehypertension, like hypertension, doesn't show signs or symptoms. Many people don't know they have it, and doctors often overlook it, Ovbiagele says.

How do you know if you have it? The only way to know is to check your blood pressure, Stein says. In otherwise healthy people, elevated systolic and/or diastolic blood pressure on two separate occasions -- taken two or three days apart -- is enough to be diagnosed with high blood pressure. You can take your blood pressure at home with a blood pressure monitor, or use the machine at your local pharmacy or grocery store, if it has one.

If it's consistently within the prehypertension range, tell your doctor so that you can get it under control before it becomes hypertension.

Taking Charge of Your Blood Pressure

The good news is, you can slow the progression to hypertension. Here's what experts recommend:

• Eat healthfully. Consider following the DASH diet, which focuses on eating more fruits, vegetables and whole grains, and less saturated fat, total fat, and cholesterol. It also restricts sodium, which can raise blood pressure, and emphasizes foods rich in calcium, potassium, and magnesium, minerals that help lower blood pressure. 
• Watch the salt. Although a recent study showed that lowering your salt intake may raise cholesterol and triglycerides, most experts still recommend cutting back on salt. Be on the lookout for sodium in canned, prepared, and processed foods. Avoid sprinkling too much salt on foods. The American Heart Association recommends limiting your intake to 1,500 mg a day.
• Move more. Get at least 30 minutes of moderate activity every day, most days of the week.
• Get to a healthy weight. Extra pounds make prehypertension more likely. Physical activity and healthy eating can help you shed extra weight.
• Limit alcohol. Try to drink no more than two drinks a day if you're a man or no more than one if you're a woman. If you don't drink, don't start.
• Curb stress. It's unclear whether chronic stress, by itself, can raise your blood pressure in the long run. But it can make you more likely to overeat and to skip exercise, Stein says. So try to change your circumstances, or at least how you deal with them, by practicing stress reduction techniques such as meditation.
• Check your blood pressure. If you can, buy a home monitor, and take your blood pressure twice day: once in the morning and once at night, Stein says. "One very high reading is concerning, but one alone isn't enough," he says. "You want to see how it changes over time."

By Winnie Yu
WebMD Feature
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