To determine whether you have hypertension, a medical professional will take a blood pressure reading.
How you prepare for the test, the position of your arm, and other factors can change a blood pressure reading by 10% or more.
That could be enough to hide high blood pressure, start you on a drug you don’t really need, or lead your doctor to incorrectly adjust your medications.
National and international guidelines offer specific instructions for measuring blood pressure.
If a doctor, nurse, or medical assistant isn’t doing it right, don’t hesitate to ask him or her to get with the guidelines.
Here’s what you can do to ensure a correct reading:
Don’t drink a caffeinated beverage or smoke during the 30 minutes before the test.
Sit quietly for five minutes before the test begins.
During the measurement, sit in a chair with your feet on the floor and your arm supported so your elbow is at about heart level.
The inflatable part of the cuff should completely cover at least 80% of your upper arm, and the cuff should be placed on bare skin, not over a shirt.
Don’t talk during the measurement.
Have your blood pressure measured twice, with a brief break in between.
If the readings are different by 5 points or more, have it done a third time.
There are times to break these rules.
If you sometimes feel lightheaded when getting out of bed in the morning or when you stand after sitting, you should have your blood pressure checked while seated and then while standing to see if it falls from one position to the next.
Because blood pressure varies throughout the day, your doctor will rarely diagnose hypertension on the basis of a single reading.
Instead, he or she will want to confirm the measurements on at least two occasions, usually within a few weeks of one another.
The exception to this rule is if you have a blood pressure reading of 180/110 mm Hg or higher. A result this high usually calls for prompt treatment.
It’s also a good idea to have your blood pressure measured in both arms at least once, since the reading in one arm (usually the right) may be higher than that in the left.
A 2014 study in The American Journal of Medicine of nearly 3,400 people found average arm- to-arm differences in systolic blood pressure of about 5 points.
The higher number should be used to make treatment decisions.
In general, blood pressures between 160/100 mm Hg and 179/109 mm Hg should be rechecked within two weeks, while measurements between 140/90 and 159/99 should be repeated within four weeks.
People in the prehypertension category (between 120/80 and 139/89 mm Hg) should be rechecked within four to six months, and those with a normal reading (less than 120/80 mm Hg) should be rechecked annually.
However, your doctor may schedule a follow-up visit sooner if your previous blood pressure measurements were considerably lower; if signs of damage to the heart, brain, kidneys, and eyes are present; or if you have other cardiovascular risk factors.
Also, most doctors routinely check your blood pressure whenever you go in for an office visit.
For more on getting your blood pressure under control, buy Controlling Your Blood Pressure, a Special Health Report from Harvard Medical School.
New high blood pressure guidelines: Think your blood pressure is fine? Think again
The American College of Cardiology and the American Heart Association certainly grabbed the attention of us busy primary care physicians when they released their updated blood pressure guidelines.
The definition of the diagnosis of high blood pressure and the decision-making process surrounding its treatment have traditionally been quite individualized (read: all over the place).
Personally, I invite these stricter measures, because they are accompanied by solid research, logistical guidance, and useful management strategies.
However, a whole heck of a lot of people just got pulled into a significant medical diagnosis.
Let’s review what’s new.
A new definition of high blood pressure (hypertension)
(Please note that all numbers refer to mm Hg, or, millimeters of mercury.) The guidelines, in a nutshell, state that normal blood pressure is under 120/80, whereas before normal was under 140/90.
Now, elevated blood pressure (without a diagnosis of hypertension) is systolic blood pressure (the top number) between 120 and 129. That used to be a vague category called “prehypertension.”
Stage 1 high blood pressure (a diagnosis of hypertension) is now between 130 and 139 systolic or between 80 and 89 diastolic (the bottom number).
Stage 2 high blood pressure is now over 140 systolic or 90 diastolic.
The measurements must be obtained from at least two careful readings on at least two different occasions.
What does careful mean? The guidelines provide a six-step tutorial on how, exactly, to correctly measure a blood pressure, which, admittedly, is sorely needed.
My patients often have their first blood pressure taken immediately after they have rushed in through downtown traffic, as they’re sipping a large caffeinated beverage.
While we always knew this could result in a falsely elevated measurement, it is now officially poor clinical technique resulting in an invalid reading.
New recommendations on monitoring blood pressure
The new guidelines also encourage additional monitoring, using a wearable digital monitor that continually takes blood pressure readings as you go about your life, or checked with your own cuff at home.
This additional monitoring can help to tease out masked hypertension (when the blood pressure is normal in our office, but high the rest of the time) or white coat hypertension (when the blood pressure is high in our office, but normal the rest of the time).
There are clear, helpful directions for setting patients up with a home blood pressure monitor, including a recommendation to give people specific instructions on when not to check blood pressure (within 30 minutes of smoking, drinking coffee, or exercising) and how to take a measurement correctly (seated comfortably, using the correct size cuff).
The home blood pressure cuff should first be validated (checked in the office, for accuracy).
If you now have high blood pressure, you may not need meds… yet
The guidelines also outline very clearly when a diet-and-lifestyle approach is the recommended, first-line treatment, and when medications are simply just what you have to do.
Thankfully, the decision is largely based on facts and statistics.
For the elevated blood pressure category, medications are actually not recommended; rather, a long list of evidence-based, non-drug interventions are.
What are these interventions? Things that really work: a diet high in fruits and vegetables (such as the DASH diet, which is naturally high in potassium); decreased salt and bad fats; more activity; weight loss if one is overweight or obese; and no more than two alcoholic drinks per day for men, and one for women.
Simply changing what you eat can bring down systolic blood pressure by as much as 11 points, and each additional healthy habit you adopt can bring it down another four to five points.
For people with stage 1 hypertension who don’t have cardiovascular disease and are at low risk for developing it (less than 10% risk of an event within 10 years), lifestyle changes are still the way to go.
(Risk is determined using a well-researched, widely used formula available here.)
However, if a patient has any kind of cardiovascular disease and stage 1 hypertension (a blood pressure over 130 systolic or 80 diastolic), or no existing cardiovascular disease but a significant risk of developing it (over 10% risk within the next 10 years), then lifestyle changes plus medications are recommended.
And, even if someone has less than a 10% risk, if their blood pressure is over 140 systolic or 90 diastolic, which is now stage 2 high blood pressure, they ought to be treated with medication as well.
Optimizing treatment of high blood pressure
The authors bring several evidence-based yet progressive concepts into the guidelines, the first of which is that high blood pressure should be treated using a team approach.
This makes sense, as science supports more and better patient education around self-monitoring, nutrition, and lifestyle changes, as well as stress management.
Telehealth is emphasized as a cost-effective method of ongoing monitoring that is more convenient for patients than frequent office visits.
And why should this all matter to you?
Mountains of research over time have shown a very clear link between high blood pressure and cardiovascular disease.
A 20-point higher systolic blood pressure or a 10-point higher diastolic blood pressure is associated with double your risk of death from a heart attack, stroke, or other cardiovascular complication (like abdominal aortic aneurysm or heart failure).
What many people don’t realize is that those who survive these events find their lives permanently altered by disability and medical complications.
Much is being made of the fact that the new definitions of high blood pressure will mean roughly half of all US citizens will be considered to have high blood pressure, but when you really look at the numbers, as cardiologists already have, not that many more people will actually be advised to take medications.
Although the public has good reason to be suspicious of “big pharma,” that’s not what this is about.
Diet and lifestyle changes are powerful medicine.
Even if your blood pressure is normal now, you can help to prevent it from becoming elevated starting today.
Eat more fruits, veggies, and whole grains, and limit foods high in sodium and unhealthy fats. Be as physically active as possible.
There is a lot more in the very long, detailed executive summary, including specific guidance for various populations, myriad diseases, and special circumstances, but this is the gist of it.