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The term “white coat” comes from references to the white coats traditionally worn by doctors. The white coat effect means that your blood pressure is higher when it is taken in a medical setting than it is when taken at home. On average, when your blood pressure is taken at home the top (systolic) number can be around 10mmHg lower than it would be if taken by a doctor and 5mmHg lower on the bottom (diastolic) number. For some people this difference can be even greater.
What causes the white coat effect?
Your blood pressure is not fixed – it rises and falls throughout the day in response to what you are doing and what is happening around you. White coat effects will often happen because you are nervous about having your blood pressure tested by a doctor or nurse. Most of us tend to feel more tense in medical settings than we do in surroundings that are familiar to us, although we do not always notice it.
The white coat effect can influence some peoples’ blood pressure more than others. If you are very anxious your systolic blood pressure can rise by as much as 30mmHg. This can make it more difficult for your doctor to get an accurate measurement of your blood pressure.
What is white coat hypertension?
The term white coat hypertension may be used if you have high blood pressure readings (i.e. readings that are consistently 140/90mmHg or above) only when you are in a medical setting. Your blood pressure readings may be normal when they are taken at home.
Sometimes it can be difficult to establish whether you actually have high blood pressure, or are just experiencing white coat hypertension.
How will I know if my blood pressure is affected?
Anyone can be affected by the white coat effect, but white coat hypertension is less common. You may be nervous or anxious about having your blood pressure taken without you or your doctor realising it. The only way to be sure is to compare readings taken in the clinic with readings that are taken at home. There are two ways of doing this.
- Measuring your blood pressure at home – You could measure your blood pressure at home. Measuring your own blood pressure regularly can be helpful as it allows your doctor or nurse to see what your readings are like outside of the clinic. Keeping a personal record of your blood pressure can help to show what your blood pressure is like from day to day.
- 24-hour blood pressure monitoring – This kind of blood pressure monitoring can show in more detail how your blood pressure changes throughout the day. You will be given a small digital monitor to wear which measures your blood pressure regularly and automatically over a day and night. Your readings are stored in its memory so you don’t need to do anything apart from keeping the monitor on. Some GP surgeries can provide 24-hour monitors; alternatively you may have to go to your local hospital outpatients department to have one fitted.
What can I do about white coat hypertension?
If you are experiencing white coat effects when having your blood pressure measured, it is important to try and manage your anxiety if you can. This might just mean resting for a while before having your blood pressure measured. If you have had to rush to your appointment or are feeling nervous, taking a moment to relax and calm down can help to bring your blood pressure back down to normal.
Sometimes it may not be possible to overcome the white coat effect. In this case your doctor will discuss options with you. To gain a clearer picture of your blood pressure your doctor may ask to see home blood pressure readings or decide to monitor you more closely for a period of time.
I have been diagnosed with high blood pressure, but could it be white coat hypertension?
Your doctor or nurse will be aware of white coat hypertension and will take it into consideration before making any diagnosis about your blood pressure.
People with white coat hypertension can go on to develop high blood pressure. For this reason it is important to have your blood pressure checked regularly (perhaps every 6-12 months with a medical professional). This will allow you to take appropriate steps to lower your blood pressure, should it start to rise.
If you have any queries or concerns about the white coat effect or white coat hypertension, speak with your doctor or nurse.