BLOOD pressure refers to the pressure generated within the arteries when blood is pumped out of the heart. Diastolic pressure is generated when the heart contracts and systolic pressure when the heart relaxes. The unit for measuring blood pressure is mm/Hg. The blood pressure for a normal healthy adult varies from one person to the other and from time to time changes - especially according to activity.

According to standards set out by the World Health Organisation, readings below 139/89mm indicate normal blood pressure. Readings between 140/90mm to 160/95mm indicate marginal high blood and those above 161/96mm are high blood pressure.

Actually, high blood pressure is more a condition than an illness and can occur in healthy people too. For example, when a person is happy, angry, sad, or feeling cold, the blood pressure gets higher as triggered by the sympathetic nerve. Therefore, to get a truly accurate indicate of whether a person's blood pressure is normal it is necessary to take the readings at different times.

Hypertension can be of a primary or secondary nature. The former constitutes 90 to 95 per cent of the cases. The causes are unknown but there is a close relation between heredity and physical makeup. Secondary hypertension is triggered by diseases: kidney disease, adrenal gland tumours, hyperthyroidism, and so forth. When the disease that is causing high blood pressure is cured, the blood pressure often resumes to normal.

Usually, there are no symptoms for high blood pressure. Most sufferers don't know that they have high blood pressure until it is measured by a physician. However, an abrupt increase of blood pressure (that is, from 160mm to 240mm) - can lead to severe headache, nausea and visual impairment.

Symptoms such as dizziness, vertigo or ringing in the ears usually have no direct relation with high blood pressure, and are more likely to be caused by mental stress. Although if those symptoms persist, a physician should be consulted.

If high blood pressure is left untreated for a long time, it can cause serious complications to the heart, brain and kidneys.

When high blood pressure is diagnosed, patients should follow the instructions of their doctors. Don't panic. Hypertension is curable.

To reduce the risk of high blood pressure or hypertension, there are several things individuals can do.

Reduce mental stress, get adequate sleep and proper exercise. Limit the consumption of tobacco and alcohol. Adopt healthy eating habits (reducing salt intake, and avoiding foods rich in fat and cholesterol).

Transcendental medication, Tai Chi, walking and maintaining appropriate weight can reduce the risk of high blood pressure.

Medication (usually diuretic drugs that suppress sympathetic nerve and blood vessel contraction) is the most effective treatment for high blood pressure, but it should be a long term objective and under the direction of one's doctor. If there are side effects to prescribed drugs, inform your doctor immediately.

For certain secondary hypertension, surgery is an effective treatment to restore blood pressure back to normal.

Above all, don't panic if you have hypertension. It is curable.

The following are answers to some of our readers' questions from doctors and health care professionals of the Hong Kong Medical Association (Co-ordinated by Administration and Support Group, Personnel Services Branch, Hong Kong Police).

If I take medication for treating chronic hypertension, will there be complications?
Long term medication for hypertension is usually very safe. A small proportion of patients - especially during the early stages of treatment when the most suitable medicine is being tried out - may react unfavourably to medication with symptoms like dizziness, fatigue, frequent urination, heart palpitations, flushing of face, swelling of legs, throbbing sensations, skin rash, etc. Occasionally people may be allergic to a prescribed drug. If medication is tolerated in the early weeks, there is seldom long term complication to anti-hypertension drugs.

Members of my family have a history of hypertension. I am middle-aged. Will I have a higher risk of getting hypertension? What preventive measures should be taken?
YES. People with a strong family history of hypertension are definitely more at risk. The way to prevent its occurrence is by controlling body weight, exercise, balanced diet, relaxing and not smoking or drinking alcohol. Those more at risk should visit their family doctor regularly and have their blood pressure measured - and treated early if required.

My wife is in the fifth month of her pregnancy. She has frequent headaches and dizzy spells. Are these the symptoms of hypertension? If she has hypertension, will there be an impact on the baby?
Hypertension is usually symptom-free in its early stages. Although headaches and dizziness are sometimes associated with hypertension, they are not diagnostic of high blood pressure. The best and most accurate way to diagnose hypertension is by the simple measurement of her blood pressure once or twice a day for a period of 1-2 weeks.
If blood pressure is persistently above 140/90, then your wife probably has hypertension and requires treatment.
In any case, regular blood pressure reading during pregnancy is highly recommended because hypertension carries a risk both for the mother and the foetus that can be avoided by treatment and control of the high blood pressure.

The next issue to be discussed in Health Is Wealth is cardiac disease. Looking forward to receiving your questions on that subject, or any thing else you would like to know about hypertension. Fax: 2865-4799.