Some patients have what is called 'white-coat hypertension;' their blood pressure is consistently elevated in the doctor's office or clinic but normal at other times. It is called this because the patient is reacting to the white coat that the doctor or other caregiver is wearing. If your blood pressure is high when measured at the doctor's office or clinic but is low when you measure it yourself, you should mention that to your doctor so that a more thorough evaluation may be done.

Sometimes in these cases ambulatory blood pressure (ABP) monitoring will be used to further measure blood pressure. These devices take readings every 15 to 30 minutes throughout the day and night while you go about your normal daily activities. An analysis of these readings will clarify the status of your blood pressure.

Source: The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. NHLBI, November 1997.