Diagnosing high blood pressure

Hypertension, or high blood pressure, is often called a ‘silent disease’ because you usually don't know you have it. There may be no symptoms or signs. Nonetheless, it damages the body and eventually may cause problems such as heart disease.

This is why it's important to regularly monitor your blood pressure, especially if it has ever been high or above the ‘normal’ range, or if you have a family history of hypertension. Because high blood pressure can cause heart disease, you may also need to be screened for your risk of  heart disease.

Measuring blood pressure

You can get your blood pressure measured by your GP or practice nurse, at most pharmacies or you can buy a blood pressure monitor to use at home.

Blood pressure is usually measured with electronic devices with an automatically inflating arm cuff, but some doctors and nurses still prefer the old fashioned aneroid sphygmomanometer, which consists of using a stethoscope, arm cuff, dial, pump and valve.

Blood pressure is described with two numbers: systolic and diastolic.

Systolic blood pressure is the pressure during a heartbeat.

Diastolic blood pressure is the pressure between heartbeats.

Blood pressure is measured in millimetres of mercury (mm Hg) and is written systolic over diastolic (for example 120/80 mm Hg, or ‘120 over 80’).

Blood pressure is not considered to be high if it is at or below 140/90 – or if it is 140/90 or more in the clinic but your daily average is below 135/85.

Hypertension is blood pressure that is greater than 140/90 and if your average away from the surgery or clinic is 135/85 or above.

Blood pressure may increase or decrease, depending on your age, heart condition, emotions, activity and the medication you take. One high reading does not mean you will be diagnosed as having high blood pressure.