Low blood pressure

The medical term for low blood pressure is ‘hypotension’ which is defined as a reading of 90/60 or lower.

Low blood pressure isn’t necessarily a bad thing as it means you have a lower risk of heart diseases and strokes. If you have low blood pressure then it generally means that you are healthy and do not have anything to worry about.

Low blood pressure is preferable to high blood pressure.

Problems of low blood pressure

Low blood pressure can cause a few problems such as fainting and dizziness. If your blood pressure drops when you stand up then there may be an underlying factor. Whatever this is, it is causing your blood pressure to suddenly drop which temporarily stops the blood supply to your brain. This results in feelings of dizziness or fainting.

Standing up for a long period of time also causes this reaction.

There are two types of low blood pressure:

• Postprandial hypotension: your blood pressure drops when you have eaten a meal. This may be caused by blood collecting in blood vessels within your abdomen during digestion.
• Postural hypotension: your blood pressure drops as you stand up from a lying down or seated position. Blood collects in the veins in your legs which temporarily stops it from reaching your brain.

The results of this are symptoms of dizziness and fainting.

Causes of low blood pressure

Low blood pressure can be causes by any number of factors which include:

• Diabetes
• Medication to treat high blood pressure, e.g. alpha blockers
• Severe illnesses which can damage the heart
• Addison’s disease (disease of the adrenal glands)
• Early stage of pregnancy
• Blood loss due to an accident or injury or loss of fluid from a burn.

Postprandial hypotension nearly always develops in older people. Postural hypotension also affects older people: this is due to the fact that their arteries narrow and harden with age. Their arteries are not able to respond as quickly as a younger person’s when they stand up which causes blood to pool in their extremities. You can also develop this if you have high blood pressure.

Diagnosing low blood pressure

Unless you present with any symptoms it is possible for this condition to lie undiagnosed for many years. But it can be easily detected by your GP if he/she measures your blood pressure during a check up.

If you have symptoms of dizziness and fainting then your GP will ask you about those and may examine you as well. He or she will also ask you about your medical history and may recommend you for further tests.

If your GP thinks you might have postprandial hypotension then your blood pressure will be measured before and after you have eaten.

If he or she thinks you have postural hypotension then your blood pressure will be measured once you stand up after sitting or lying down. You may also be referred for a ‘tilt test’.

The tilt test is performed at a hospital and involves you lying down on a table (you are securely fastened to this table) which is slowly tilted. Your blood pressure is measured as this table tilts upwards.

Treating low blood pressure

If you have naturally low blood pressure then treatment will not be required.

But if you have postprandial hypotension or postural hypotension then treatment will be needed although this will depend on what has caused either of these. Postprandial hypotension can be treated by medication which constricts your veins to prevent blood from collecting there. You will also be asked to lie down after meals to prevent any dizziness and fainting and to eat little and often. Avoid large, carbohydrate rich meals. Postural hypotension is also treated with medication. Your GP may prescribe a drug which increases the amount of salt you retain although this has to be done very carefully. Too much salt in your diet can cause high blood pressure.

You will also be asked to do the following:

• Avoid excessive or strenuous exercise
• Stand up slowly after sitting or lying down, especially first thing in the morning.
• Avoid standing still for long periods of time
• Wear special compression stockings
• Try not to have a very hot bath or shower
• Increase your fluid and salt intake but be careful regarding the amount of salt you have. Your GP will advise you about this.

You will be asked to try these at home. If these do not work then medications such as those described above will be prescribed.

Low blood pressure is not usually a problem and preferable to high blood pressure.

High blood pressure is discussed in the next section onwards.