A phenomenon called masked hypertension
But for some people, the opposite occurs: Their blood pressure is normal at their medical appointment but elevated the rest of the day.
This phenomenon is called "masked hypertension." The best way to uncover it is to wear a small monitoring device for 24 hours, researchers said.
For this new study, the researchers had almost 900 healthy, middle-aged patients do just that.
The result: Almost 16 percent who had "normal" blood pressure at the clinic learned otherwise after around-the-clock monitoring.
"In working individuals who are not being treated for hypertension [high blood pressure], our data show that ambulatory blood pressure is usually higher than clinic blood pressure," said lead researcher Joseph Schwartz. He is a professor of psychiatry and sociology at Stony Brook University in Stony Brook, N.Y.
"It is critical that we learn what, if anything, should be done to lower their ambulatory blood pressures," he said.
Elevated blood pressure contributes to stroke, heart failure, vision loss and kidney failure. "Thousands of people die from high blood pressure every year," Schwartz said.
Ambulatory blood pressure is measured when you're walking around, living your normal life. The results may be a better indicator of health risks than clinic blood pressure, the study authors said.
A difference in readings is most common for young, lean people. The gap shrinks substantially by age 60 or as overweight people become obese, the findings showed. ■