New guidelines redefine high blood pressure

Nov. 21, 2017—Did you have high blood pressure last week? You might have it now, even if your numbers have changed.

That's because the definition of high blood pressure has changed. A high systolic pressure has switched to 130 mm Hg or higher. A high diastolic pressure is now 80 mm Hg or higher.

Systolic is the top number in a blood pressure reading. Diastolic is the bottom number.

Previously, having either a top number of 140 or higher—or a bottom number of 90 or higher—indicated high blood pressure.

The new guidelines come from the American Heart Association (AHA) and the American College of Cardiology. They mean that about half of U.S. adults now have high blood pressure, or hypertension. That's a jump from about 1 in 3 adults having high blood pressure.

The new numbers reflect the health problems that can occur between readings of 130–138/80–89 mm Hg. Damage to blood vessels happens soon after blood pressure goes up.

New blood pressure categories

High blood pressure causes the second largest number of preventable heart disease and stroke deaths, according to the AHA. The new definitions are designed to alert people to take steps to lower their blood pressure earlier.

The new blood pressure categories are:

  • Normal: Top number less than 120 and bottom number less than 80.
  • Elevated: Top number 120–129 and bottom number less than 80.
  • Hypertension stage 1: Top number 130–139 or bottom number 80–89.
  • Hypertension stage 2: Top number at least 140 or bottom number at least 90.
  • Hypertensive crisis: Top number over 180 and/or bottom number over 120.

The new guidelines do away with the category of prehypertension. This term was used to define blood pressure with a top number between 120 and 139 or a bottom number between 80 and 89. People who once had prehypertension might now fall into the elevated or stage 1 categories.

Effects of the new guidelines

Although the number of people with high blood pressure has taken a big jump, the AHA doesn't believe the number of people who need to take medication will change that much. Most people should be able to lower their numbers by making lifestyle changes.

Younger people may feel the effect of the new guidelines the most. The number of men under age 45 with high blood pressure is expected to triple. The number of women under age 45 with high blood pressure will likely double.

The guidelines also stress the need to assess blood pressure properly. Numbers should be based on an average of two to three readings on at least two different occasions.

This is the first major update of blood pressure guidelines since 2003. You can read the new guidelines in Hypertension.