When you have high blood pressure the last thing you need is stress, which makes your blood pressure shoot right up. Unfortunately, when you are worried about your blood pressure, having it checked by a doctor or nurse is quite stressful. In fact, some people only have a high reading when their blood pressure is taken in the surgery, and have perfectly normal readings when their blood pressure is measured outside of the clinical environment. This phenomenon is known as white coat hypertension.
What causes white coat hypertension?
White coat hypertension is due to stress. Stress causes your blood pressure to rise by triggering the production of adrenaline (epinephrine) hormone. This constricts your arteries and veins and makes your heart beat more quickly, so both your blood pressure and pulse rate increase.
The stress response that causes blood pressure to rise is part of the fight or flight reaction. This adaptive response boosts blood pressure and heart rate to supply your muscles and brain with more blood, oxygen and nutrients so you are more able to fight or flee in dangerous situations. This effect is usually short-lived, so that if your doctor waits a few minutes and checks your blood pressure again, your blood pressure comes back down to normal as you feel more relaxed.
In people with white coat hypertension, however, the high blood pressure does not come back down immediately as the effects of stress are excessive and prolonged.
White coat hypertension can cause the systolic blood pressure (higher reading) to rise as much as 100 mm Hg, although this is extreme. More often, white coat hypertension increases systolic blood pressure by 20-30 mmHg, and diastolic blood pressure (the lower reading) by 10 mmHg to 20 mmHg.
This chart shows the typical 24 hour blood pressure variation in someone with white coat hypertension. It shows the normal fall in blood pressure that occurs during sleep, the surge in blood pressure that occurs just before waking, and the spike in blood pressure associated with white coat hypertension when visiting the clinic to have their blood pressure taken.
You can see 24-hour charts for someone with normal blood pressure, and someone with untreated high blood pressure by clicking HERE.
White coat hypertension is common
High blood pressure due to white coat hypertension is more common than previously realised.
Research published in the Journal of Hypertension assessed 163 people with mild to moderate hypertension whose blood pressure was checked in a clinic on eight separate occasions.
An astonishing three out of four (75%) people had substantial white coat hypertension on at least one occasion, in which their office BP reading was at least 20 mmHg systolic (or 10 mmHg diastolic) greater than blood pressure measurements obtained from home.
One third of those tested consistently had substantial white coat hypertension on three or more occasions.
White coat hypertension is an important sign
Until recently, white coat hypertension was thought to be relatively harmless. Now, it’s recognised that white coat hypertension is a sign of over-sensitivity to stress which can play havoc with your circulation. White coat hypertension causes arteries to lose their responsiveness to natural regulation signals when they are subjected to a blood pressure that varies considerably and is sometimes high, sometimes low and sometimes normal.
Latest research suggests that people with White Coat Hypertension have just as many abnormalities of the heart and blood vessels, such as stiffness and poor contraction of the left ventricle of the heart and decreased elasticity of artery walls, as those with persistently high blood pressure. People with white coat hypertension are also highly likely to develop severe hypertension in the future.
When white coat hypertension is suspected, it is confirmed by wearing a 24-hour BP ambulatory monitoring tape and recording stressful events in a diary to show how your blood pressure responds during stressful conditions. If you have white coat hypertension, this will show that your blood pressure rises when measured by a doctor, but falls back down into the normal range afterwards.
If you are diagnosed as having white coat hypertension, it is important to monitor your blood pressure regularly yourself, at home, and to make diet and lifestyle changes to both improve your blood pressure control and improve your ability to cope with stress through relaxation such as meditation and aromatherapy.
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Image credits: s_photo/shutterstock; kurhan/shutterstock