Health Library

Categories > Heart Health > Blood pressure

The lowdown on high blood pressure

You may be hearing more about high blood pressure, or hypertension, in the news lately. For one thing, it’s a common condition, affecting one in three American adults, and a leading risk factor for heart disease, kidney damage, stroke and impaired vision, including blindness. High blood pressure is more common in African-Americans, who tend to develop it at an earlier age and suffer a more severe condition.

But the condition is making headlines because another 45 million people are now considered at risk for developing hypertension thanks to guidelines issued in 2003 by the National Heart, Lung, and Blood Institute. The change created a new category called “prehypertension” level, which includes persons with blood pressure readings that fall between 120/80 mm HG and 139/89 mm HG—levels previously considered normal. Normal levels are now defined as below 120 over 80.

What’s going on? In recent years, researchers concluded a few new things about blood pressure. The likelihood of developing hypertension over your lifetime is much higher than previously thought. Even those who do not have high blood pressure by age 55 still have a 90 percent risk for developing the condition, according to one study.

Researchers also found that damage to the arteries begins at a lower pressure once considered optimal. High blood pressure is called a silent killer because it usually shows no symptoms. By identifying people as prehypertensive, doctors can help those who fall in that category to take steps now to prevent developing high blood pressure. While high blood pressure can’t be cured, it can be controlled by lifestyle factors and medication.

Your blood pressure is the force of your blood against the walls of your arteries as it courses through your body. This force normally rises and falls throughout the day, but when it remains elevated, your blood pressure is considered high. Hypertension causes:

  • arteries to stiffen or harden, which makes the heart work harder to pump blood through the body
  • weakened vessels to bleed or rupture, such as in the brain or eyes, leading to stroke or blindness
  • blood vessels in the kidneys to narrow and thicken, impairing the kidneys’ ability to filter wastes from the blood

What the numbers mean

When your doctor takes your blood pressure, he or she measures the force of your blood in two ways, hence, the two numbers of your reading. Your systolic pressure refers to the force of the blood in the arteries as the heart beats. (Pressure is calibrated in millimeters of mercury, or mm HG.) The diastolic pressure refers to the force of the blood in the arteries as the heart relaxes between beats.

You needn’t have both numbers in the high range to be considered hypertensive. For people ages 50 and older, the systolic number, which tends to rise with age, becomes more important. If only your systolic number is high, the condition is called isolated systolic hypertension and leads to the same health problems as with standard hypertension. The diastolic number tends to decrease with age, so for younger people, this reading is more important. If you have diabetes or chronic kidney disease, a pressure of 130/80 or more is considered high.

What to do?

If you are one of the 45 million Americans who now find themselves in the prehypertensive category, your doctor will likely recommend several lifestyle changes to head off further trouble. Among them:

  • Lose weight or maintain a healthy weight.
  • Eat healthy foods, including more vegetables, fruits and nonfat dairy products.
  • Reduce salt intake.
  • Increase physical activity.
  • Limit alcohol.
  • If you smoke, quit.

If your pressure is high, you’ll need to take more aggressive action. In addition to prescribing the lifestyle changes above, your doctor may recommend one or more blood pressure-lowering drugs. These include angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers, beta-blockers, calcium channel blockers, diuretics and vasodilators.

Tips for an accurate reading

  • Don’t smoke or drink coffee or other caffeinated beverages at least 30 minutes before having your pressure taken.
  • For five minutes before the test, sit with your back supported and feet flat on the ground. Rest your arm on a table at heart level.
  • Wear short sleeves.
  • Go to the bathroom before the test. A full bladder can change your reading.
  • Get two readings at least two minutes apart and average them.

Source: National Heart, Lung, and Blood Institute