Hypertension or high blood pressure is known as the "silent killer" because despite being one of the most common fatal conditions worldwide, most people are unaware they have the condition because it presents with very few or no symptoms.

Diagnosis is therefore often not made until the disease has progressed enough to cause symptoms, at which stage it often has life threatening outcomes such as stroke. Because of the lack of specific symptoms, adults should have their blood pressure measured every five years.

Blood pressure

Blood pressure is the pressure exerted against the walls of blood vessels as the heart pumps blood through them. An increased blood pressure means too much strain is being placed on the artery walls which can lead to complications such as a stroke, kidney damage or heart attack.

Blood pressure is measured in millimetres of mercury (mm Hg) using an instrument called a sphygmomanometer. There are two numerical figures of blood pressure - the systolic pressure and the diastolic pressure. The systolic pressure is the higher figure and indicates the pressure of the blood when the heart beats.

Diastolic pressure is the lower figure and indicates the pressure of the blood when the heart rests between two beats. A normal blood pressure level is one of around 120/80 mm Hg while a pressure over 140/90 mm Hg is considered high.

Risk factors and symptoms

The risk of hypertension is increased in people who are overweight or obese, those of African or Caribbean origin and those with a diet high in salt but low in fresh fruits and vegetables. People who do not get enough exercise, who smoke or drink too much alcohol or who are aged over 65 years are also at an increased risk. High blood pressure also runs in families.

Diagnosis and treatment

Hypertension is measured using a sphygmomanometer which may be used to regularly monitor the blood pressure level in someone who is diagnosed with the condition. There are several groups of antihypertensive medication that can be used to control blood pressure.

Over time, high blood pressure can damage organs such as the kidneys, eyes and brain and these are routinely examined for hypertension-induced damage.