What do blood pressure numbers mean?

Originally Published: October 5, 1995 - Last Updated / Reviewed On: July 4, 2014
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Alice,

What does a large split in blood pressure numbers mean? For example, a 26 year old male with a reading of 143/73.

Signed,

Pumping

Dear Pumping,

With all the health recommendations out there, it's tough to keep the numbers straight. The cutoff point or "magic number" to remember for normal blood pressure is 120/80. It's not really important how far apart the two numbers are, but whether or not each one is within the healthy range.

The first number of a blood pressure reading is the systolic pressure, when the heart is pumping. The second or bottom number is the diastolic blood pressure, when the heart is relaxed between beats. The units, mm Hg, simply stand for millimeters of mercury. According to the National Heart, Lung, and Blood Institute (NHLB), healthy adults over age 18 should have a blood pressure measurement that's less than 120/80. If your systolic measurement is over 120 mm Hg or your diastolic measurement is over 80 mm Hg, then you have an increased risk of high blood pressure, also known as HBP or hypertension. Hypertension can be primary or secondary. Primary (or essential) hypertension tends to develop gradually over many years. Secondary hypertension can appear suddenly and is typically associated with an underlying condition such as kidney problems, thyroid problems, or alcohol abuse.

This chart from the NHLB summarizes the different blood pressure categories:

Category

Systolic in mmHg
(top number)

 

Diastolic in mmHg
(bottom number)

Normal

Less than 120

and

Less than 80

Prehypertension

120 to 139

or

80 to 89

Stage 1 HBP

140 to 159

or

90 to 99

Stage 2 HBP

160 or higher

or

100 or higher

In your example, a measurement of 143/73 falls in the category of Stage 1 HBP. However, this isn't necessarily cause for alarm. Blood pressure readings vary depending on factors such as stress, excitement, anxiety, and setting. Therefore, health professionals recommend that you calculate your blood pressure from an average of three readings on separate days. Since you only gave one example for a 26 year-old man, it may not be possible to determine from one reading whether you have HBP. For a more precise picture of your health, getting a few more readings and then asking your provider if your results show the possibility of a problem with hypertension might prove beneficial. Here are some tips to prep for your blood pressure test to ensure an accurate reading:

  • Avoid coffee, caffeinated drinks, and smoking at least 30 minutes prior to the test
  • Use the bathroom before being tested
  • Take time to relax in the seat before the test to reduce movement during the test
  • Bring a list of medications and supplements you are currently taking (both prescription and over-the-counter) as some have the potential to raise your blood pressure

Many factors can put people at an increased risk of hypertension, including diet, obesity, alcohol abuse, tobacco use, physical and emotional stress, environment, and psychological and genetic factors. The good news is that many of these factors can be adjusted, which is how people are able to lower their blood pressure with advice from a health care provider and some lifestyle changes.

If you're a Columbia student, you can contact Medical Services (Morningside) or the Student Health Service (CUMC) to make an appointment to speak with a health care provider and get another reading. For some additional information on hypertension and blood pressure, check out the related Q&As.

Here's to keeping your heart healthy, whether you're pumping iron or pumping up a blood pressure cuff.

Alice