I agree its best to monitor one's BP at home, where you have control over the environment. A doctor's office is not exactly the most stress-free environment!
Consider the stress of just getting there, oftentimes battling traffic, parking, etc, then dealing with office staff, calling you sugar plum, sweet pea, etc, then being told you can't be seen until you pay your remaining bill, which HAS been paid in full weeks prior, then standing there while they call billing to get an update (seems they could have updated your account before your appointment), then being told you can't be seen that day because you were LATE for your appointment (when you were there ahead of time, you had to wait for them to get their records straight)
Finally a p'od "nurse" takes you back to an exam room, acts annoyed you don't walk faster, throws a bunch of papers at you and walks out, slamming the door behind her. Per Nurse Ratched's instructions, you have dutifully changed into the fashionable paper gown, and wait another hour. Then you poke your head timidly out the door and ask when you will be seen, only to be snapped at again, then, finally someone comes in to take your blood pressure. Ok, of course its sky high!
Then in walks Dr Wonderful, who observes you're a little high strung today. Oh, that explains your high BP---white coat syndrome!
The above described at least 80% of the doctor visits I had in the past, while my BP hovered in the danger zone. Finally I bought a BP monitor, monitored myself at home, and got consistently high readings. I also found a new doctor! When I took in a PO of my readings, he didn't argue or suggest
whitecoat" he just put me on BP meds, monitoring, etc.
Its incredible how doctors seem to come up with just about any excuse to brush your symptoms off and blame/belittle you for even suggesting they might be missing something!