White-coat hypertension, blood pressure that is only elevated in a clinical setting, and masked hypertension, blood pressure that is normal in a clinical setting but high elsewhere, are two conditions that can affect the accuracy of your blood pressure readings during your doctor’s appointments.

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If you’re like most people, you feel nervous whenever you visit your physician’s office. After all, it’s only natural to be a little anxious about any tests you’ll have to undergo or the news your doctor will deliver. Add to that the stress you experience from traffic problems on your way to the office or any factors at home that force you to be late for your appointment, and it’s no surprise when your blood pressure is elevated when your doctor measures it.

If you aren’t taking antihypertensive medications and your blood pressure is elevated only when measured in your doctor’s office or another clinical setting, you have white-coat hypertension. The term “white-coat effect” is used for people on antihypertensive therapy who have high blood pressure when measured in the office but not outside the office. The American Heart Association (AHA) notes that 15 to 30 percent of people with blood pressure elevations measured in a doctor’s office have white-coat hypertension, named because of the white coats many health-care professionals wear.

In the past, white-coat hypertension was viewed as a relatively harmless finding; however, some evidence suggests that people with white-coat hypertension may advance to sustained hypertension more rapidly than those with normal office and out-of-office blood pressure readings, and that white-coat-hypertension indeed may be cause for concern. Some experts now believe that the white-coat effect is indicative of blood pressure that frequently becomes elevated at times of stress, which over time damages blood vessels and leads to full-blown hypertension and increases cardiovascular risk.

Study Suggests White-Coat Hypertension Is Not So Innocuous

Left untreated, white-coat hypertension may increase the risk of cardiovascular events and death, according to a recent study in Annals of Internal Medicine. Researchers analyzed data from 27 studies involving a total of 25,786 people with untreated white-coat hypertension or treated white-coat effect and 34,487 people with normal blood pressure. The study participants underwent in-office and out-of-office blood pressure monitoring and were followed an average of three to 19 years. Compared with people who had normal blood pressure, the participants with untreated white-coat-hypertension faced a 36 percent increased risk of cardiovascular events, a 33 percent greater risk of death from any cause, and more than double the risk of death from cardiovascular causes, the study found. No significant association was found for people with treated white-coat effect, however.

Masked Hypertension: The Other Side of the Coin

On the flip side of the white-coat phenomenon is masked hypertension, or blood pressure readings that are normal in a clinical setting but high elsewhere. The AHA notes that masked hyperten­sion may occur in about 15 to 30 percent of adults whose office blood pressure readings are in the normal range. As with white-coat hypertension, masked hypertension can make diagnosing hypertension more difficult. In one study, researchers found that 16 percent of the participants with normal clinic blood pressure had masked hypertension found on ambulatory monitoring. Masked hypertension was more common in men than women, people with prehypertension, and younger, normal-weight participants versus older, overweight people, according to the study.

Also, like white-coat hypertension, masked hypertension may portend increased cardiovascular risk, and some studies suggest that it’s associated with an incidence of cardiovascular events comparable to that among people with sustained hypertension, says the AHA.

Based on these study findings, if you have white-coat hypertension or masked hypertension, talk with your physician about 24-hour home blood pressure monitoring. This testing can help determine whether your blood pressure is elevated only at the doctor’s office or outside the office—or whether it’s persistently high and requires medical treatment.

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