Don't know, but from what I've read, as this kind of thing is in the news a lot lately what with smartwatches and other devices being sold for home checking, most of them are in fact not very reliable. They are useful anyway because big changes can get one to the doc and it might save their lives, but accuracy isn't that great. Also, some people test higher for BP at the doc's. Don't know why, but it seems to make a lot of people anxious and their BP goes up. The nurse sounds very wise.
So, I'm one of those people that has to worry about developing high blood pressure. Sigh. Wish it weren't true but it is familial. I researched best cuffs for at home. I didn't want to spend a fortune so got something in the 50 dollar range. Omron is a good brand according to my doctor, so that is what I got. My doctor has me chart my bp. So, what I'm supposed to do is to sit with feet flat on the floor, hands at chest level and think happy thoughts while taking my bp, THREE different times a day. It can be at any time, early, mid day and evening. Record them all. They are never the same. But it gives a general idea of where your blood pressure is at that doctors then can use.
White coat syndrome is when your bp seems like it is higher in the doctors office. Before I started checking my bp, I had hoped that was the case. Definitely anxiety can make bp higher and mine goes a bit higher at the doctors. But the truth is, I have a bp that wants to go high. I have to watch it and work on it.
I have “White Coat Syndrome”… my BP is almost always higher in the doctor’s office than it is at home. If it’s “too” high in the doctor’s office, he will sit and chat with me for a few minutes until I relax, then check it again. It’s always down considerably.
My husband’s doctor had him check his BP for a while and we actually took our machine to one of his doctor’s appointments. Our machine (purchased at the pharmacy about 10 yrs ago) was almost exactly what hubby’s doctor’s machine read.
In addition, my doctor sent home a BP monitor that automatically sent my readings straight to his office because he was worried about a couple of high readings. I was to check my BP 3 times/day and each time the readings were sent via internet to the doctor’s office. Quite a few times over a 6 week period, I took my BP on the machine from the doctor’s office, the immediately took it on my own machine. I wouldn’t expect the readings to be the same since I’d moved around, changing cuffs, etc but they were always very close. I feel quite confident that my home machine is pretty accurate.
I’d wonder if your problem was really White Coat Syndrome and by the time the nurse checked your BP the second time, you’d calmed down enough for the reading to drop. Just a guess, so I’d advise having your doctor keep a close eye on it for awhile.