"White coat hypertension" is a well-documented phenomenon in which a patient's blood pressure can be significantly higher than usual when taken by a physician.
According to a study published in the December 2001 issue of the American Journal of Hypertension, when a physician records the blood pressure of a patient with white coat hypertension, the systolic, or upper, reading may be as much as 26 points higher than the usual blood pressure. The diastolic, or lower, reading may be as much as 16 points higher. Researchers discovered two ways to help combat this problem. The first was to have a nurse take the blood pressure rather than a physician. The second and most accurate method was to have patients measure their blood pressure with a portable device at home several times throughout the day.