Grocery store blood pressure machine accurate?

Dear Alice,

What is normal blood pressure for a 24 year old male? Are the blood pressure machines found in supermarkets reliable?

— Anxious

Dear Anxious,

Monitoring your blood pressure in general (at a supermarket or doctor's office) is a good idea, but before you get worked up about what your numbers are, there are some things you should consider.

Blood pressure is expressed as a fraction, the systolic pressure and the diastolic pressure. The systolic pressure (the top number in the fraction) is a measurement of the pressure in the arteries when the heart contracts and pumps blood from the heart to the lungs and body. The diastolic reading measures the pressure in the arteries in between heart contractions, as the blood flows from one chamber to another. In a healthy young adult the normal systolic pressure ranges from 90 to 119, and the normal diastolic pressure ranges from 60 to 79. According to the National Heart, Lung and Blood Institute, a diagnosis of high blood pressure includes a diastolic reading of over 139 and/or a systolic reading of over 89. What about that gap between normal and high blood pressure? Having a systolic reading in the 120 to 139 range or a diastolic reading in the 80 to 89 range is referred to as prehypertension (hypertension being the medical name for high blood pressure).

Technically, a diagnosis of high blood pressure only comes after being tested multiple times at different times of the day, or even on different days, as any one reading can be affected by  a number of factors, including temporary anxiety or excitement. Although machines in supermarkets and pharmacies may be accurate, there is also a chance that they may not be calibrated as regularly as the machines in doctors' offices, and therefore they may not be as reliable.

If you have used one of these machines, don't jump to any conclusions. Instead next time you visit a health care provider, you can mention that you are curious about your blood pressure reading and that you want to be sure that it is normal. Good for you in wanting to stay on top of your health. A little bit of prevention goes a long way — especially with our circulatory systems. Here's hoping your numbers are in the healthy range!

Last updated Mar 26, 2015
Originally published Mar 23, 1995

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