'White coat syndrome' sees blood pressure mis-diagnosed
22 February 2011 Last updated at 18:57 GMT
Thousands of patients are being wrongly diagnosed with high blood pressure because they find the experience of going to the doctor so stressful.
It is known as White Coat syndrome and now doctors in England and Wales are being advised to order extra tests to see if a patient's blood pressure stays high even when they are back at home.
Jane Hughes reports.