Care Advice : Hypertension

General Practice

What is hypertension?

Systolic blood pressure is the pressure exerted upon the walls of blood vessels when the heart contracts, while diastolic blood pressure is one when the heart relaxes. Blood pressure is measured in millimetres of mercury (mmHg).

Hypertension is a condition in which the systolic blood pressure is persistently higher than or equal to 140 mmHg or diastolic blood pressure is persistently higher than or equal to 90 mmHg.

Hypertension can be divided into “primary (essential) hypertension” and “secondary hypertension” based on different causes:

  • Primary (essential) hypertension: the cause of high blood pressure is unknown, generally related to risk factors including ageing, unhealthy eating habit, obesity and physical inactivity
  • Secondary hypertension: mainly caused by an identifiable underlying secondary causes, such as kidney diseases or endocrine disorders

It is estimated that around 27% of the population aged 15 or above in Hong Kong suffers from hypertension.

What are the symptoms of hypertension?

  • Most people with hypertension do not have obvious symptoms and it is usually detected in a routine body check. A small number of patients may have symptoms of headache, dizziness and fatigue.
  • Since hypertension cannot be identified easily, adults should have blood pressure measured at least once every 2 years, for early detection of the disease.

Why do I sometimes get different blood pressure readings when I use sphygmomanometer to measure two blood pressures consecutively?

  • Blood pressure will change according to physiological conditions or surrounding environment. The blood pressures will also be affected by body posture and mood.
  • Under normal circumstances, even if the same sphygmomanometer is used for two consecutive blood pressure measurements, there may be a deviation blood pressure of several degrees. It is acceptable as long as the blood pressure can be controlled within the target range.

Why is the blood pressure measured at the clinic higher than the blood pressure measured at home?

  • Many patients feel nervous and stressed in the clinic environment resulting in elevated blood pressure. After adapting to the clinic environment or establishing a harmonious relationship with the medical staff, the repeated blood pressure measured may fall back to the true level.
  • If the blood pressure measured in the clinic is consistently higher than that measured at home (i.e. the systolic blood pressure is 20mmHg higher or diastolic blood pressure is 10mmHg higher), the patient may have a white-coat effect. You may need to consult a doctor for professional advice.

What home blood pressure record does the doctor want?

Before the next consultation, please measure your blood pressure at home for one whole day every week. It is best to measure the blood pressure in the morning and evening at home on the day. The recommended measurement time is one in the morning (from 6 am to 9 am) and one in the evening (from 6 pm to 9 pm), with readings recorded. You can refer to the following table for example of the record form:

DateTimeSystolic pressureDiastolic pressurePulse

Risk factors for Hypertension:

There are different risk factors for developing hypertension at various stages of life, such as:

  • Ageing
  • Overweight and obesity
  • Unhealthy eating habits and excessive salt intake
  • Physically inactive
  • Smoking
  • Excessive alcohol intake
  • Family history of hypertension, particularly among first degree relatives.

How to prevent hypertension?

Prevention of hypertension starts with good living habits:

  • Beware of the intake of salt in daily diet.
  • Eat more vegetables and fruits.
  • Quit smoking and reduce alcohol intake.
  • Weight control.
  • Regular exercise: lack of exercise will affect the flexibility of blood vessels, which causes stiffening of the vessels and induces hypertension.
  • Keep your mind relaxed.

Follow up:

Remember to follow up as scheduled.

Should you have any doubt, please consult your doctors or nurses.

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