On the other hand, about 10 percent of people have lower blood pressure in the doctor's office than they do at home. These people may need to be on medication but their doctors won't know it if they just rely on office measurements.
There's good medical evidence to back all this up. Four out of five large studies of home blood pressure monitoring found that it was better than office measures for predicting problems like heart attacks or strokes.
Still, assuming you have "white coat hypertension" is no excuse for ignoring high blood pressure. Patsy McDermott, a family physician practicing in Malibu, Calif., has seen patients try to dismiss high numbers.
"A lot of times people will have high blood pressure in the office, and they say, 'It's only high when I come here.' However, there are all kinds of stressors throughout the day, not just trips to the doctor. To verify what's going on when you're not here, the home cuffs are good."
There are two main kinds of blood pressure monitor available: the traditional upper-arm style and the one that goes around your wrist. The wrist monitors are easy to use, and more and more people are buying them. They're also more likely to give inaccurate numbers, according to the American Heart Association, and aren't generally recommended.
"There are a lot of monitors out there, and some of them aren't very good," Goff said, warning that even upper-arm monitors could be inaccurate. "Patients should take their device to their doctor or nurse to make sure it agrees pretty well with the device being used in the office."
Dr. John D. Bisognano, a cardiologist at the University of Rochester Medical Center, agrees that wrist monitors can be problematic. "If the patient uses the monitors with great precision and reproducibility, they work okay," he said by e-mail. "But if not, the readings can vary widely and cause unnecessary alarm to the patient and provide inaccurate data. They may have some limited use in overweight patients who cannot obtain accurate readings using arm monitors, even with a large cuff."
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