A blood pressure chart is only useful if your blood pressure has been measured accurately and the reading is not misleading. But if you think getting your blood pressure measured in the doctor’s office is the best and most accurate way to determine your TRUE blood pressure, think again. You might be surprised to know measurements taken in the clinic are the LEAST likely to be accurate and to predict your risk for heart disease and other high blood pressure complications. There is now overwhelming scientific evidence that using a home blood pressure monitor is superior to “in-office” blood pressure measurements, according to a joint scientific statement from the American Heart Association and the American Society of Hypertension published in the journal Hypertension.[1] The major recommendation by the expert panel, chaired by Dr. Thomas Pickering of Columbia University, was this: if you have hypertension or borderline hypertension, you should be using a home blood pressure monitor on a regular basis. Only then will using a blood pressure chart to classify your blood pressure be worthwhile.

Determine your TRUE blood pressure with a home blood pressure monitor and accurate blood pressure chart

In part 1 of this series, you learned why the measurement of blood pressure at clinics is rarely done properly, even when using an accurate blood pressure chart. In fact, the standard method for measuring blood pressure by a doctor or nurse in a clinic setting is often “inadequate or even misleading.”[1] Couple that fact with the great minute-to-minute variability in your normal blood pressure, and you can see why in-office checks can fail to accurately assess your true blood pressure and why doctors incorrectly classify patients based on the most current blood pressure chart. Only by using a home blood pressure monitor can you get a more accurate picture of your true blood pressure and correctly classify your blood pressure utilizing a blood pressure chart.

Click here to view or print our Blood Pressure Chart showing the classifications of blood pressure according to experts as well as a Log Chart for Good Blood Pressure Monitoring at Home

Self-monitoring at home is also superior for assessing your actual risk for high blood pressure complications like heart disease or strokes and for judging the effectiveness of a medication or other pressure-lowering strategy. And because utilizing a home blood pressure monitor involves you more in your own care, it can bolster your efforts to make changes and take your treatment seriously.

What is your TRUE blood pressure?

Your TRUE blood pressure is one that is the average over an extended period of time, and thus it can best be assessed by taking regular readings at home. Blood pressure fluctuates significantly depending on the time of day, your activities, and other factors. Normal blood pressure fluctuates continuously in a 24-hour period, and the variability is influenced by many physiological factors. In fact, blood pressure can easily change by more than 20 mmHg between readings. Using a home blood pressure monitor on multiple occasions will tell you your true, average blood pressure over prolonged periods of time. (You can find out exactly how to properly do this in part 3).

Using a home blood pressure monitor is a superior way to diagnose prehypertension and the various stages of hypertension as outlined in the blood pressure chart. The American Heart Association, the American Society of Hypertension, the European Society of Hypertension, and other groups all admit the difficulty of determining people’s true blood pressure on the basis of one or two measurements at the time of an office visit. These respected organization all recommend home blood pressure monitoring in order to get an initial, reliable estimate of your true blood pressure.

White coat and masked hypertension are common conditions that can only be diagnosed with a home blood pressure monitor

By measuring at home, you can determine whether you have “white coat” or “masked” hypertension. White-coat hypertension is characterized by an elevation in clinic blood pressure compared to the true readings on a home blood pressure monitor and is often due to the anxiety or fear of being at a doctor’s office or having the measurement done in front of a doctor or nurse.  On the other hand, people with masked hypertension have the opposite problem: normal clinic blood pressure and elevated readings on a home blood-pressure monitor. Both of these conditions are now known to be relatively common but are impossible to diagnose without home measuring; you can’t tell if you have white coat or masked hypertension by only comparing your in-clinic blood pressure readings to those on a blood pressure chart.

Measuring at home gives you more accurate information about prehypertension

Your true blood pressure determined by regular use of a home blood pressure monitor will also give you more accurate information about borderline hypertension, or “prehypertension,” as it is officially termed. Prehypertension is defined as a blood pressure of 120–139/80–89 mmHg when taken in the clinic setting, as you can see on the blood pressure chart. Technically, it’s not “high” at this level, although it is in a range that is still associated with significantly increased risks compared to those with “normal” blood pressure. Since prehypertension is close to the borderline between normal and high, it’s more difficult to diagnose in the doctor’s office where only one or two measurements are taken and where blood pressures can easily read higher or lower than then do outside of the clinic setting. Prehypertension is associated with a more than two-fold increase in the risk of cardiovascular disease as compared with those with blood pressure levels below 120/80 mmHg.[3]

Additional advantages to home blood pressure monitoring

Because it is more accurate, more reliable, and better able to determine your true blood pressure, home blood pressure monitoring is also a better predictor of your actual risk for having a stroke, heart attack, or some other serious problem related to high blood pressure, such as kidney disease.[4] Another important advantage of regularly using a home blood pressure monitor is in guiding the treatment decisions you make with your doctor. By knowing your true, accurate blood pressure, you and your doctor can make better decisions about whether you really need treatment, which treatment is best, and whether your current treatments are working as they should.

In part 3 of this article, you’ll get tips on how to correctly use a home blood pressure monitor, how to get an initial, reliable estimate of your “true” blood pressure, and how to interpret a blood pressure chart based on home measurements. Once you do this, you know whether you have a true problem with high blood pressure requiring treatment. If you do have high or borderline-high blood pressure, remember the first line therapy is always drug-free and natural. Read about drug-free, natural treatments for high blood pressure here.

[1] Hypertension. 2008; 52: 10-29.

[2] JNC-7 Complete Report. Hypertension. 2003;42:1206.

[3] Lancet. 2002; 360:1903 – 1913.

[4] Hypertension. 2010 Jun;55(6):1346-51.

Click here to view or print our Blood Pressure Chart showing the classifications of blood pressure according to experts as well as a Log Chart for Good Blood Pressure Monitoring at Home

Originally published in 2013, this blog has been updated.