You're sitting in the GP's office and the GP suggests measuring your blood pressure. "That's fine," you think as they put the cuff on your arm. "It's always been normal in the past."
The strange sensation of the cuff tightening around your arm makes you feel uncomfortable. You don't remember it being so tight the previous times, but it will be over soon. Once the cuff deflates, you look over to the GP to see what they would say and they tell you that the blood pressure seems a bit high…
This is how it starts for most patients who eventually get diagnosed with high blood pressure, also known as hypertension. While a single high blood pressure reading is not enough to form a judgement, patients who have high blood pressure consistently are often diagnosed with the condition.
White Coat Hypertension: Do you really have high blood pressure?
Usually when GPs obtain a single high blood pressure reading, it is prudent to repeat blood pressure measurements at least a few times on that visit to ensure it is not an outlier. I've also heard it said that the ideal is for the doctor to even leave the room while the blood pressure is taken! Though I've never seen that done in actual practice.
If it remains high despite multiple trials, your GP may decide to bring you back on another day to repeat your blood pressure reading. Perhaps it was the coffee you drank that morning or the fact that you were talking excitedly or about to receive a vaccine and felt apprehensive about the needle. Even if the blood pressure remains high on multiple visits, it still doesn't necessarily mean you have high blood pressure.
You may have heard of the white coat effect and it really does affect some patients. It may even affect you, whether you are aware of it or not. You may think you're relaxed and comfortable, but even being in the different environment of a consultation room can have the effect of raising blood pressure.
If blood pressure readings are high in the clinic on more than one occasion, it is time to pursue a diagnosis. Do you truly have blood pressure, or is it just white coat?
One Easy Trick: Home Blood Pressure Monitoring
At this point, it is probably ideal for home blood pressure to be measured in some form. One method is using a 24 hour ambulatory blood pressure monitor available through most pathology services at a cost. If these are ordered by the GP, the final report displays beautiful graphs of your blood pressure over a 24 hour period amongst various other statistics (example on page 3 of this article).
As useful as this is, there are some limitations. For example, a GP makes the decision to start you on blood pressure medication after confirming hypertension using the 24 hour monitor. On following visits, the medication has been increased further but the blood pressure only improves slightly. Is this inadequate treatment or a component of white coat again?
Over the course of a few years, patients may be started on blood pressure medication, change medications, increase or decrease in weight… many factors can improve or worsen blood pressure control over a period of time. While it is possible to repeat ambulatory blood pressure every time major changes occur, my preference is to lean towards investing in a home blood pressure machine.
Taking Measurements into Your Own Hands
Usually around the same cost as a single ambulatory blood pressure test, a patient can invest in a blood pressure machine from the local pharmacy. Additionally, blood pressure machines are generally covered by private health insurance with supporting letter from the GP.
While these machines need to be calibrated occasionally, over the long term they prove an invaluable tool to help us diagnose and manage hypertension. In short, it gives the patient more control in monitoring their own condition and helps us consistently track how their actual blood pressure is going.
In future weeks, I will discuss how home blood pressure monitoring is performed, and some broader thoughts on its role in managing hypertension.
Broader Reading: Beyond the Basics
Quite an old but interesting Australian study, showing that 16 of 62 patients newly diagnosed with hypertension in fact had normal blood pressure on ambulatory monitoring and did not actually require blood pressure medication.
Some more recent findings show that untreated white coat hypertension may cause increased risk of heart disease, which directly contradicts suggestions from a previous study. While this doesn't mean GPs should overtreat individuals who don't need medication, it does present some nuance to monitoring of individuals with white coat hypertension. This can be an interesting point of discussion with your GP.
What do patients feel about undergoing ambulatory blood pressure testing? Can we predict what demographic has white coat hypertension? This article provides some interesting insights.
