A condition in which blood pressure is high in the doctor’s office but generally seems to be normal at other times. Many experts believe that nervousness may be responsible for this temporary rise in blood pressure. Opinions differ, however, as to whether the condition may be safely ignored.
Blood pressure is measured in terms of millimeters of mercury (mm Hg). According to the American Heart Association, a person has high blood pressure, or hypertension, if the systolic pressure — the pressure in an artery when the heart contracts to pump blood out — is 140 mm Hg or higher or if the diastolic blood pressure — the pressure in an artery when the heart relaxes to let blood flow in — is 90 mm Hg or higher. This threshold level is often written simply as 140/90 mm Hg.
Hypertension raises the risk of developing coronary heart disease or of having a stroke. In people with diabetes, this risk is increased. Hypertension also heightens the risk of such diabetic complications as eye disease (retinopathy) and kidney disease (nephropathy). The American Diabetes Association recommends that most adults with diabetes get their blood pressure below 140/80 mm Hg. Treatment to achieve this may involve making changes in lifestyle or taking certain drugs.
Researchers have not obtained conclusive evidence as to whether people whose blood pressure is elevated only in the doctor’s office should undergo treatment. While some studies suggest that white coat hypertension is harmless, other research indicates that this condition merits treatment, since the individuals studied showed signs of developing physiological changes that typically occur in people with persisting hypertension. An Italian study, for example, found evidence that in people with white coat hypertension the left ventricle, the chamber of the heart that pumps blood to the body, may be enlarged, with thickened walls.