High Blood Pressure

Blood pressure is the pressure exerted on the walls of the arteries when the heart pumps; the term “systolic” is the top reading on a blood pressure monitor and relates to the maximum pressure exerted on the artery when the heart contracts, and the term “diastolic” is the bottom number and is the minimum pressure exerted on the artery when the heart relaxes. Both the systolic (top reading) and diastolic (bottom reading) are important:


for adults aged 40 to 69

every 20 mmHg increase in systolic blood pressure

or 10 mmHg increase in diastolic blood pressure


the risk of death from coronary artery disease

High blood pressure (hypertension) is a very common condition, affecting 1 in 4 adults in the UK and 70% of people over 70 years of age. There is a direct relationship between high blood pressure readings and the incidence of coronary artery disease and stroke:

half of coronary artery disease cases

and two thirds of stroke cases

are due to raised blood pressure

Blood pressure changes throughout the day, tending to be highest in the morning and lowest in the evening. It can rise transiently with stress and will be higher during physical activity than before.

30-40% of patients who have high blood pressure readings with a doctor are actually suffering from “white coat hypertension” and have normal blood pressures outside of a clinic setting, and equally 15% of people have “masked” hypertension, where blood pressure is normal with a doctor but high elsewhere. Diagnosis of hypertension should therefore not be based on readings obtained during an isolated visit to the doctor, unless the blood pressure readings are exceptionally high, or there is evidence that blood pressure has been sustained at a high level for some time, resulting in damage to kidneys or eyes, or in heart muscle thickening.

The most recently published UK guidelines issued by NICE, the National Institute for Health and Care Excellence, advocate the use of ambulatory blood pressure monitoring to confirm or refute a diagnosis of hypertension, with treatment recommended at the following thresholds:

Category Systolic Diastolic
Office BP ≥140 and/or ≥90
Ambulatory BP (awake readings) ≥135 and/or ≥85
Home BP average ≥135 and/or ≥85

Related links:

Tests - Blood and Urine

Blood and urine tests can be very useful for diagnosing a vast number of conditions, and also for checking that a medication is working properly and not causing any adverse effects on the liver or kidneys. Read more

Tests - Echocardiography

Echocardiography is the study of the heart using ultrasound. Similar to a scan of a baby undertaken during pregnancy, an ultrasound probe applied to the chest wall can be used to study the heart. Read more

Tests - Ambulatory BP Monitoring

An ambulatory blood pressure monitor will obtain a series of blood pressure readings during the monitoring period (usually 24 hours), which will allow the doctor to determine whether a patient’s blood pressure is consistently high enough to require treatment. Read more

Treatments - Medical Therapy: High Blood


There is a degree of discord internationally regarding the thresholds for treatment, and the UK guidelines do differ slightly from their European and American counterparts. Read more

Education and Support - Hypertension

Resources for patients who are concerned about their blood pressure. Read more

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