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Hypertension

Introduction

Blood pressure is the pressure inserted on blood vessels during contraction and relaxation of the heart. This pressure is usually described in terms of millimeter mercury (mmHg). The pressure recorded during contraction of the heart is called "systolic blood pressure" (sBP), and the pressure recorded during relaxation of the heart is called "diastolic blood pressure" (dBP).
sBP is usually around 120 mmHg and dBP around 80 mmHg, it is commonly recorded as 120 / 80. Normal blood pressure is not static, it fluctuates throughout the day, and varies with different levels of exercise and emotions.

Situation in Hong Kong

Hypertension is common in Hong Kong. The Population Health Survey 2003/2004 revealed that 27.2% of the population aged 15 and above have hypertension. The prevalence of hypertension increases with age, from 5.2% for people aged 15-24 to 73.3% for people aged 75 and above.

Definition of hypertension

Hypertension is persistent elevation of blood pressure above the normal range. It is defined as sBP 140 mmHg or above, and/or dBP 90 mmHg or above. This standard is applicable to all adults 18 years old and above. Occasional elevation of blood pressure above the normal range should not be considered as hypertension. If you have doubt, seek medical advice. However, once the diagnosis of hypertension is made, it is necessary to take long-term medications to control the blood pressure (usually for life), to prevent complications.

Causes of hypertension

  • 90% of hypertension has no definite cause and is called "primary hypertension". The risk factors described below may be related to the disease
  • 10% of hypertension is secondary to other diseases, such as renal diseases and endocrine disease

Risk factors

Various factors during the life course may increase the risk of hypertension, for example:

  • Smoking
  • Overweight & obesity
  • Physical inactivity
  • High salt intake
  • Excessive alcohol intake
  • Ageing
  • Family history (first degree relative) of hypertension

Symptoms

  • Majority of patients have no symptoms, usually only discovered during a routine check up or until complications develop
  • Extremely high blood pressure may cause symptoms like dizziness, visual disturbance, headache and fatigue

Complications of uncontrolled hypertension

Untreated hypertension can lead to complications like heart failure, coronary heart disease, stroke, and renal failure. Uncontrolled hypertension is a silent killer. Early diagnosis and proper treatment can effectively prevent or delay the complications.

Regular blood pressure monitoring

Hypertension seldom causes symptoms, so routine blood pressure measurement is of value in detecting hypertension

Blood pressure classification Blood pressure (mmHg) Recommendations
Systolic Diastolic
Normal Less than 120 Less than 80 Recheck in 2 years
(Annual check for adult aged >75 years)
Pre-hypertension 120 to 139 80 to 89 Recheck in 1 year
Hypertension 140 or above 90 or above Seek medical advice as soon as possible

Management of hypertension

The management of hypertension depends on the commitment of the patient to participate proactively in self-management and adopting healthy lifestyle practices:

  • Take medication as instructed (which is usually life-long), attend regular medical follow-up
  • Self-monitoring of blood pressure
  • Stop smoking
  • Maintain optimal body weight and waist circumference
  • Healthy eating: Reduce salt intake and eat more fruits and vegetables
  • Increase physical activity
  • Reduce alcohol intake
  • Proper stress management

For more information on hypertension, please visit the websites "Hong Kong Reference Framework for Hypertension Care for Adults in Primary Care Settings 【Patient Version】" & "Tips on preventive care for older adults in primary care settings" (Chinese version only) or consult your doctor.