Many people are diagnosed with hypertension even though their blood pressure is perfectly normal. Doctors do this every day to perfectly healthy people. In the UK, doctors are now being advised on using a more accurate method before diagnosing any patient with hypertension.

Blood pressure changes from minute to minute depending on what you're doing or how stressed you are. Your pressure will rise with emotional stress, physical activity, and stimulants such as cigarettes and coffee. Even talking raises it. That's how it should be. Your body is behaving normally. Pressure rises naturally when more blood needs to be delivered to your brain for thinking, your legs for walking, your stomach for eating etc. To get an accurate reading you need to be relaxed. It's your readings at rest that matters.

The cuff should be put round your arm when you feel under no emotional or physical stress. You've been sitting down comfortably for at least 5 minutes. You're not talking during the reading.

You've not had a cup of coffee (or any drink containing a lot of caffeine) for at least 2 hours and you haven't had a cigarette for at least 30 minutes.

And you mustn't be someone who suffers with white coat hypertension. If you do, the reading will be meaningless. Some people get so nervous at having their blood pressure taken that their pressure shoots up just at the thought of having that horrible cuff squeezed tighter and tighter around their arm. If you are a nervous type and this applies to you, your pressure has probably gone up just from reading this!

Also at least 2 readings should be taken at intervals before a diagnosis is made. Ideally several readings should be taken on each arm to get a true picture.

You're a bit skeptical. I can sense it.

"Surely no doctor would diagnose me with hypertension unless he or she was absolutely sure?"

Well hear this. A group of researchers writing in America's leading medical journal, The Journal of the American Medical Association found that over 1 in 5 people diagnosed with borderline hypertension had in fact perfectly normal blood pressure.

How did they know this? Simple. They put these 'patients' on an ambulatory blood pressure monitor (ABPM). This is a computerized device that you wear for 12 - 24 hours. It takes your readings automatically every 15 or 30 minutes and records them. With this monitor you get a truer picture of your blood pressure.

On 29th March, 2011 the BBC had the headline: Doctors cause a third of stubborn high blood pressure. They reported that 37% of 8,295 patients thought to have stubborn or resistant hypertension actually had "white coat" hypertension.

If I were diagnosed with borderline hypertension 140-150/90-95 I don't think I'd accept that diagnosis without an ABPM especially if it meant being put on prescribed medication.

In fact in August, 2011 The National Institute for Health and Clinical Excellence (NICE) advised doctors in England and Wales to move towards "ambulatory" monitoring of patients at home.

So you see, the question, high blood pressure, do you really have it, is not quite as dumb as it sounds especially if you have no symptoms, which is usually the case.

Make sure you don't find yourself taking prescription medication when you don't need it. If you have borderline hypertension, insist on an ambulatory monitor.