High Blood Pressure | Diagnosis & Tests

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Learn More About High Blood Pressure Diagnosis & Tests

Blood Pressure Monitoring at Home

Using an Ambulatory Blood Pressure Monitor

How is high blood pressure diagnosed?

The only way to know whether your blood pressure is too high is to check it with a blood pressure monitor. The higher your blood pressure is, the more often you need to check it.

Your doctor will measure your blood pressure at more than one visit to see if you have high blood pressure. When you first start treatment to lower your blood pressure, your doctor may want you to come to the office regularly. Your blood pressure will be checked at the office.

You may also be asked to check your blood pressure at home and keep track of your numbers for your doctor. High-quality, automated arm blood pressure cuffs for home use can be purchased for about $40 to $60. Your doctor may want you to check your blood pressure several times a day. Another option is to have you use an ambulatory blood pressure monitor.

How often should I have my blood pressure checked?

After age 18, have your blood pressure checked at least once every 2 years. Do it more often if you have had high blood pressure in the past. Your doctor may even ask you to monitor your blood pressure at home.

What do the numbers mean?

Blood pressure is really two measurements, separated by a slash when written, such as 120/80. You may also hear someone say a blood pressure is "120 over 80."

The first number is the systolic blood pressure. This is the peak blood pressure when your heart is squeezing blood out. The second number is the diastolic blood pressure. It's the pressure when your heart is filling with blood­ — relaxing between beats.

A normal blood pressure is less than 120/80. High blood pressure is 140/90 or higher. If your blood pressure is between 120/80 and 140/90, you have what is called "prehypertension," which means that if you don’t take important steps, your elevated blood pressure can turn into high blood pressure.

Hypotension, or low blood pressure, happens when your systolic pressure is consistently below 90, or 25 points below your normal reading.

  Systolic (first/top number) Diastolic (second/bottom number)
Normal

Less than 120

Less than 80

Prehypertension

120–139

80–89

High blood pressure: Stage 1*

140–159

90–99

High blood pressure: Stage 2

160 or higher

100 or over

*If you have diabetes or kidney disease, what is considered high blood pressure may be lower than for other people. Talk to your doctor about what is considered high blood pressure for you.

Bibliography

See a list of resources used in the development of this information.

Written by familydoctor.org editorial staff

Reviewed/Updated: 08/12
Created: 01/96

Learn More About High Blood Pressure Diagnosis & Tests

Blood Pressure Monitoring at Home

Using an Ambulatory Blood Pressure Monitor

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