You are here: Home > Education > High Blood Pressure FAQs - Expanded

Further questions and answers on high blood pressure & hypertension>

Importance of monitoring blood pressure

Questions and answers are grouped under the following headings:

  1. General Background, Definitions and Physiology
  2. Consequences of High Blood Pressure
  3. Causes of High Blood Pressure
  4. Measuring Blood Pressure
  5. White Coat Hypertension
  6. Risk Factors
  7. Investigation of High Blood Pressure
  8. Treating High Blood Pressure

1. General Background, Definitions and Physiology

How common is High blood pressure?

High blood pressure is a worldwide condition of almost epidemic proportions. For most doctors it is the single most common chronic disorder encountered in practice. It has been estimated that in Western countries somewhere between 15 and 20 per cent of the adult population have high blood pressure. Blood pressure usually rises with age and a blood pressure that would be considered abnormally high in a ten-year-old might be satisfactory in a seventy-year-old person.

High blood pressure is relatively rare in children, but very common in old age. Among young adults, men are more likely to have it than women. With increasing age sexual equality reasserts itself and approximately 40 per cent of both men and women in the fifty-five to sixty-five age group have higher than normal pressure on initial examination, and if you are over 60 years of age, the likelihood is that you will have higher than normal blood pressure.

High blood pressure during pregnancy is a special problem. However, it can be said here that if you have not previously had high blood pressure but develop it during the last few months of pregnancy the chances are that pressure will return to normal after the baby is born.

How do you know if you have high blood pressure?

Approximately 50% of those with high blood pressure are unaware that they have it. For most people with high blood pressure there are no tell-tale symptoms. In fact, the majority of people with this condition have no symptoms whatsoever. This means, therefore, that high blood pressure is usually diagnosed by chance, for instance at a routine physical check-up requested by an insurance company or new employer. Or your doctor may take the opportunity to measure your blood pressure when you happen to be in his surgery on a quite unrelated matter, such as a cold or backache.

On such a visit, if your doctor overlooks the blood-pressure check, tell him you would like to know what your blood pressure is. It will only take a minute or two to measure it. Make a note of his answer, as it may be useful to have this information in the future. If your pressure is normal your doctor will probably say that you can wait another twelve months or more before you need to have another check. On the other hand, if your pressure is higher than normal you should listen carefully to his advice and ask about anything that you don't fully understand.

What does it mean?

One of the first things to get clear is what is meant by the words high blood pressure or hypertension, as it is also called. You may hear your doctor use this word and it is as well to know that both terms mean the same and can be used synonymously. I feel it is better not to use the term hypertension because it tends to suggest an association with stress or tension - I prefer to use the words high blood pressure. Also, I prefer to regard high blood pressure as a risk factor rather than a disease, or illness, though, if untreated, it can lead to very serious illnesses.

There are two components of blood pressure: when the heart is contracting the pressure is highest, and when the heart is relaxing the pressure is at its lowest point. The unit of measurement used internationally in blood pressure measurement is the millimetre of mercury (mmHg). If your doctor tells you that your blood pressure reading is, say, 160 over 110, he will probably write this down as 160/110mmHg. He may also take a reading when you are lying down since blood pressure may vary with position, especially if certain drugs are being taken. It also varies from person to person so it is hard to define normal blood pressure.

The importance of finding out

The small but significant number of untreated people who arrive in the doctor's surgery already suffering from one or other of the serious complications of high blood pressure shows that there is a great need for early detection. Many cases of stroke occur in people whose high blood pressure has never been treated effectively and sometimes they have never even had their blood pressure measured. Similarly, most doctors know of patients whose heart attacks or kidney failure might well have been avoided if they had had treatment for their high blood pressure.

A major stroke can kill or it can leave a person severely incapacitated and unable to cope on his or her own. The family will suffer as the patient becomes dependent on relatives and it is all too easy to visualize the economic consequences of the breadwinner becoming unemployable at, say, fifty years of age.

What should you do?

If you have never had your blood pressure checked it is obviously a good idea to ask your doctor to check it on your next visit.

A number of symptoms are sometimes associated with high blood pressure but, as I have said, high blood pressure itself rarely causes symptoms. If you suffer from headache, dizziness, fatigue or nosebleed, it does not necessarily mean that you have high blood pressure. You should however report such symptoms to your doctor and he may then check your pressure, but these all occur almost as frequently in people with normal blood pressure.

Let us assume, however, that although you feel fit and healthy your doctor has found a high reading. One of the first things you will want to know is what exactly is high blood pressure?

Click here to go back to the top

2. Consequences of High Blood Pressure

Why should I bother to have my blood pressure measured?

High blood pressure causes insidious silent damage to the blood vessels and the heart. If untreated, this damage progresses over time leading to the development of stroke and heart attack. These dreaded complications of high blood pressure occur at a younger age in people with high blood pressure than in people with normal blood pressure.

Can stroke and heart attack be prevented?

The answer is - YES! The reason doctors want to detect people with high blood pressure is that it now well established that if high blood pressure is brought down to normal the damage to the cardiovascular system is halted and reversed, and stroke and heart attack are prevented, or at least postponed. Other risk factors, such as high cholesterol, smoking and overweight, must be dealt with.

Click here to go back to the top

3. Causes of High Blood Pressure

What causes high blood pressure?

For most people with high blood pressure - say 90% - there is no demonstratable cause for the elevation of pressure, and in most cases it is genetically determined, that is there is a hereditary tendency often indicated by a family history of high blood pressure. In a small number of people a cause can be demonstrated by using special investigations. This cause may be in the kidney or in the endocrine system - the glands that secrete the hormones controlling blood pressure - but in most people there is no cause.

Click here to go back to the top

4. Measuring Blood Pressure

How can blood pressure be measured?

Blood pressure is measured with an instrument known as a sphygmomanometer. The traditional sphygmomanometer consists of a cuff, which is wrapped around your arm and then inflated to a certain pressure with a hand pump. The pressure is read in millimetres of mercury read on a glass column. As the pressure is released, sounds may be heard with a stethoscope placed over an artery on the front of the arm - the brachial artery; this is the pressure when the heart contracts - the systolic blood pressure, and when the sounds disappear, the lowest pressure when the heart is relaxing is reached - the diastolic blood pressure. However, automated devices are replacing the traditional method of blood pressure measurement, and your doctor may use one of these, or recommend that you measure your own blood pressure with an automated device.

What will my doctor do?

When you go to see your doctor and ask for your blood pressure to be checked, a sphygmomanometer will be used to measure your blood pressure. Your doctor or a nurse will measure your blood pressure in the following way:

  • You should rest for five minutes before measurement
  • You should refrain from smoking or ingesting caffeine for 30 minutes prior to measurement
  • You should be seated with your feet flat on the floor with your back supported
  • Your arm should be resting on a table and be at heart level
  • Your doctor will select a cuff size appropriate for the circumference of your arm - if you have a large arm, a large cuff will be used to avoid underestimating your blood pressure and if you have a very thin arm, a smaller cuff will be used to avoid overestimating your blood pressure
  • If your doctor does not use a mercury sphygmomanometer it is important that any alternative automated device has been fully validated for accuracy
  • At least three readings will be taken with an interval of two minutes between each

If your blood pressure is normal you will be reassured and asked to return in a year or so for a further check - all our blood pressures rise with age! If your blood pressure is high, you will probably be asked to return for a repeat blood pressure measurement, and if this is high you may be sent for some investigations, including ambulatory blood pressure measurement over 24-hours (ABPM) which will tell your doctor if the blood pressure rise is sustained, or merely a response to the circumstances of measurement - white coat hypertension. If this is the case, you may be reassured but will be asked to return, perhaps in a year, for a repeat assessment.

If your doctor decides that you do have high blood pressure, you may be sent for some further investigations and treatment with tablets may be started.

What figure constitutes high blood pressure?

There is a move away from relying excessively on so-called blood pressure measurements - those obtained, for example, on your first visit to a doctor. It is now known that blood pressure taken under such circumstances may be unduly high due to anxiety, but that it may return to normal as soon as you leave the medical environment. This is called 'white coat hypertension'. For this reason your doctor will want to measure your blood pressure on a number of occasions and he/she will probably want to have a recording of your blood pressure made over 24-hours - ambulatory blood pressure measurement (ABPM), before making a decision either to diagnose you as having high blood pressure, or to prescribe treatment. A general figure for normal blood pressure is that the systolic pressure should be below 140mmHg, and the diastolic pressure below 90mmHg. These figures are lower for ambulatory blood pressures. If you have diabetes or cardiovascular disease, such as a previous heart attack or stroke, it is imperative that your blood pressure is brought down to normal and when these illnesses are present your doctor will try to achieve even lower levels of normality. The best blood pressure level is the lowest that can be tolerated without side effects.

Click here to go back to the top

5. White Coat Hypertension

What is white coat hypertension?

White coat hypertension occurs in as many as 20 per cent of people with high blood pressure. What happens is that these people have a high blood pressure in the presence of a doctor or nurse, or in a hospital, but when they get away from the medical environment their blood pressures return to normal. We speak of the white coat reaction to characterise those people with high blood pressure whose blood pressure is higher in the medical environment than outside it. This condition only became apparent with the development of devices capable of measuring blood pressure over 24-hours. So your doctor may ask you to have ABPM, as it is called, to see if your blood pressure is really what it appears to be with conventional measurement.

Is white coat hypertension harmless?

White coat hypertension is not normal, otherwise, we would all have it, but people with white coat hypertension are at much lower risk than people with sustained elevation of blood pressure. However, they may develop high blood pressure later in life. So whereas people with white coat hypertension may not require drug treatment at the time of diagnosis, they may later develop sustained high blood pressure, and annual checks on blood pressure are therefore important. Of course, when other risk factors are present, these should also be modified.

Click here to go back to the top

6. Risk Factors

What are risk factors?

It is now recognised that the cardiovascular system - the heart and blood vessels - are affected by certain risks in the circulatory environment, in much the same way as we are at risk from floods, storms and fast cars in the general environment. These risk factors include: 

  • Family history
  • Smoking
  • Age
  • Excessive alcohol intake 
  • High blood pressure 
  • Excessive salt intake 
  • High blood cholesterol
  • Obesity
  • Diabetes mellitus
  • Lack of exercise
  • Stress 
  • Certain drugs

What can I do about these risks?

The short answer is - quite a lot; sometimes much more than your doctors can do for you! You should simply identify the risks that you have and try to correct them. You should have your cholesterol and blood sugar checked in case these are abnormal. High blood pressure and high cholesterol often go hand-in-hand. You should leave the salt cellar off the table; you should stop smoking; if your alcohol intake is high, you should moderate this; if you are overweight, you should try to achieve normal body weight, and you should take regular exercise. The role of stress is more debatable but you should make time for relaxation in your life.

How serious a risk is cholesterol?

It has been proven conclusively that high blood pressure is a serious risk for developing arterial disease, and that lowering cholesterol reduces heart attack and stroke. Like high blood pressure, there is often a family history of cardiovascular disease in people with high cholesterol levels. Drugs, known as the 'statins' are now available for lowering high blood cholesterol levels but your doctor will usually start by asking you to reduce your dietary intake of foods that are high in cholesterol. These are mainly dairy produce, shellfish and poultry.

How serious a risk is smoking?

The short answer is - very serious! It is probably as important as high blood pressure. So if you smoke over 20 cigarettes a day and have high blood pressure, you can perhaps as much as halve your risk by giving up cigarettes. If you cannot stop smoking completely, try to reduce down to 10 cigarettes a day.

How serious a risk is salt?

The answer is that the evidence is accumulating to indicate that salt is an important factor in causing high blood pressure. Our intake of salt and cholesterol is too high. So do not add salt to your food and check the salt content of the foods you buy. So-called 'junk' foods can be very high in salt.

How serious a risk is weight?

People who are overweight have higher blood pressures than thin people and reducing weight helps to bring your blood pressure down. In people who are very overweight it becomes difficult to measure blood pressure accurately because of the increased arm circumference.

How serious a risk is alcohol?

High blood pressure in people who drink heavily tends to be more difficult to treat. If alcohol consumption is moderate - 20 units per week for men and 14 units per week for women - it generally does not affect blood pressure.

What about diabetes?

High blood pressure often occurs in patients with diabetes. When this happens it is very important that blood pressure is very well controlled because the damage caused by high blood pressure is accelerated when diabetes is also present. So, if you have diabetes your doctor will be particularly careful about controlling your blood pressure, and, of course, your diabetes also.

Should I take exercise?

Most people with high blood pressure can lead perfectly normal lives, except for having to modify risk factors and perhaps take a tablet each day. So if you like exercise, your doctor will encourage you to continue with this. If you don't take much exercise you will be encouraged to do so. The evidence that exercise prevents cardiovascular disease may not be as convincing as the risks already discussed, but it certainly helps to improve a sense of general well being and is encouraged as part of a programme of risk factor modification.

Click here to go back to the top

7. Investigation of High Blood Pressure

What investigations will be done?

Your doctor will first take your history and examine you. You will be sent for an examination of your urine and blood to exclude kidney disease and diabetes mellitus, and you will have a fasting blood test to determine the level of your cholesterol and other fats in the blood. Your doctor may arrange for you to wear a small device that will record your blood pressure over 24-hours, or you may be asked to measure your blood pressure at home. You will also have an electrocardiograph (ECG or EKG), and possibly echocardiography; these tests give information on the state of your coronary arteries and the size of the pumping chamber of your heart - the left ventricle - which may enlarge to cope with the high blood pressure. If your doctor suspects an underlying cause for your high blood pressure he may refer you for some specialised tests, but this is only necessary in a small number of people with high blood pressure.

Click here to go back to the top

8. Treating High Blood Pressure

Will I need tablets?

This depends on the level of your blood pressure and perhaps also on the effect that the rise in blood pressure has had on your heart and blood vessels. Other factors will also be taken into account, such as your family history, and the presence of other risks, such as smoking, overweight or diabetes.

But why tablets?

If your doctor told you that a tablet was available to prevent ageing, you would rush out to get it - along with everyone else! This is exactly what blood pressure lowering drugs do - they prevent premature ageing of the cardiovascular system, on which the brain, heart and every other organ depend for survival. If you look on blood pressure lowering tablets in this way, you will see them as a preventive measure against premature ageing, rather than as 'treatment' for an illness. I tend to regard high blood pressure as a 'risk factor' rather than an 'illness' and rather than referring to people with high blood pressure as 'patients' I see tham as having a risk factor for the future - one which can be reversed, thereby preventing ageing of the cardiovascular system, but one which if unchecked can lead to serious illness.

What drugs will I be given?

You may not need any drugs. Sometimes risk factor modification alone may be sufficient, especially when blood pressure elevation is mild. However, if you need drugs, your doctor has a broad selection to choose from. The choice will be influenced by a number of factors, such as the level of your blood pressure, a history of asthma, heart disease, diabetes or gout, in which certain drugs are especially good, but others may be contraindicated.

How often will I need to take tablets?

Most drugs for lowering high blood pressure are effective over the 24-hour period, so you will probably only need to take a tablet in the morning.

Will I need more than one tablet?

In many people high blood pressure, one tablet taken in the morning will suffice, but when high blood pressure is severe or resistant to treatment, more than one tablet may be required. There is evidence that low doses of two blood pressure lowering drugs are more effective than either given alone, and combination preparations are commonly used to reduce blood pressure. Again these are usually given as one tablet daily.

Can I expect side effects from tablets?

All drugs can cause side effects, but blood pressure lowering drugs have been improved greatly over the last decade, so that they exert their blood pressure lowering effect without producing unwanted effects. Nonetheless, we each react differently to medication, and in a small number of people with high blood pressure, one or other drug will cause symptoms. What is important is that if you develop what may be side-effects you should tell your doctor rather than suffering in silence or stopping the drug. An alternative drug can then be selected which will not cause unwanted effects.

Will my sex life be affected?

Possibly, for two reasons. First, high blood pressure itself may reduce sexual drive, and secondly, some drugs that lower blood pressure also reduce libido. If this happens be sure to discuss it with your doctor.

How will I know if the tablets are being effective?

There are four ways in which your doctor can assess the effect of the blood pressure lowering drug you are taking. First, your blood pressure can be measured at return visits to your doctor, but this is not always an accurate indication because of the white coat reaction. Alternatively, you may measure your own blood pressure at home and this gives a broader estimate of blood pressure reduction over time. Ambulatory blood pressure measurement (ABPM) over 24-hours gives the most comprehensive assessment of the efficacy of the drug you are taking, especially if this can be compared with a record taken before treatment was started. ABPM also shows if the drug is being effective over the 24-hour period, and it can detect any excessive lowering of blood pressure. Finally, your doctor can assess the longer-term effect of treatment by showing that abnormalities of the cardiovascular system, such as enlargement of the ventricular pumping chamber of your heart on echocardiography, which were present before treatment, are no longer present after a period of time on treatment.