white-coat hypertension
Some people's blood pressure rises just from being in a doctor's office, the way a heartbeat quickens before public speaking. White-coat hypertension is this effect made measurable: the pressure reads high in the clinic but is consistently normal when measured at home or over a full day. The name comes from the traditional white coat of physicians.
It is not simply an artifact to ignore. To confirm it, clinicians compare clinic readings with out-of-office measurements, using either a 24-hour ambulatory monitor or validated home readings. If the in-clinic values are elevated while the out-of-office values sit clearly in the normal range, the pattern is white-coat hypertension.
People with this pattern carry, on average, a somewhat higher long-term cardiovascular risk than those with truly normal pressure everywhere, though lower than people with sustained hypertension. For that reason they are usually not started on blood-pressure drugs immediately but are monitored over time, since some eventually develop genuine sustained hypertension.
Its mirror image is masked hypertension, where clinic readings look normal but out-of-office pressure is high; that pattern is easier to miss and carries clear risk, which is why out-of-office measurement is so valuable.