High Blood Pressure Diagnosis

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Everyone age 3 or older should have their blood pressure checked by a healthcare provider at least once a year. Your provider will use a blood pressure test to see if you have consistently high blood pressure readings.

How to prepare for a blood pressure test

Your health care provider will use a blood pressure test to see if you have higher-than-normal blood pressure readings. The reading is made up of two numbers, the systolic number and the diastolic number. These numbers are measures of pressure in mm HG (millimeters of mercury). To learn more about systolic and diastolic pressure, visit How the Heart Works.

A blood pressure test is easy and painless and can be done in the provider’s office or clinic. The provider uses a gauge, stethoscope, or electronic sensor and a blood pressure cuff to measure your blood pressure.

Prepare for the test by following a few simple steps.

• Do not exercise, drink coffee, or smoke cigarettes for 30 minutes before the test.
• Go to the bathroom before the test.
• For at least 5 minutes before the test, sit in a chair and relax.
• Make sure your feet are flat on the floor.
• Do not talk while you are relaxing or during the test.
• Uncover your arm for the cuff.
• Rest your arm on a table so it is supported and at the level of your heart.
• If it is the first time your provider has measured your blood pressure, you may have readings taken on both arms.

Even if you do prepare, your blood pressure reading may not be accurate for other reasons.

• You are excited or nervous. “White coat hypertension” refers to blood pressure readings that are higher in a doctor’s office than readings at home or in a pharmacy. Providers can detect this type of high blood pressure by reviewing readings from the office and from other places.
• Your blood pressure tends to be lower when measured at a provider’s office. This is called masked high blood pressure. When this happens, your provider will have difficulty detecting high blood pressure. Your provider can recognize this type of high blood pressure by looking at readings taken at the office and at home, especially at night.
• The wrong blood pressure cuff was used. Your readings can be different if the cuff is too small or too big. It is important for your healthcare provider to track your readings over time and ensure the correct pressure cuff is used for your sex and age.

You can also take your blood pressure at home or at a pharmacy. Measure Your Blood Pressure has more information about measuring your blood pressure outside of the healthcare provider’s office.

What the numbers mean

For most adults, a normal blood pressure is less than 120/80 mm Hg. Your blood pressure is considered high when you have consistent systolic readings of 130 mm Hg or higher or diastolic readings of 80 mm Hg or higher.

Talk to your healthcare provider if your blood pressure readings are consistently higher than 120/80 mm Hg.

NHLBI-supported research has shown that systolic blood pressure greater than 120 mm Hg can be increasingly harmful to health. Readings above 180/120 mm Hg are dangerously high and require immediate medical attention.

For children younger than 13, blood pressure readings are compared with readings common for children of the same, age, sex, and height.

Blood Pressure Levels

You may be diagnosed with high blood pressure based on your medical history and if your blood pressure readings are consistently at high levels. You may also need more tests to look for medical conditions that could cause high blood pressure or to see if high blood pressure has affected your kidneys.

Medical history

Your provider will want to understand your risk factors and get general information about your health — such as your eating patterns, your physical activity level, and your family’s health history — to develop a treatment plan for you. They will ask questions to see if high blood pressure has caused you any health problems. This will help determine if you need to undergo any tests.

Confirming high blood pressure

To diagnose high blood pressure, you will need two or more blood pressure readings at separate medical appointments.