Think back to the last time you visited a doctor's office. Certain things seem to happen by rote. They weigh you. They measure your height. And they nearly always slap a blood pressure cuff around one arm and take a reading.

Right there is where medical providers usually make one of their biggest mistakes. Having taken one blood pressure reading, they go on to the next step in their examination process. They should stop, and spend a few moments testing your other arm as well. 

Why bother with two annoying blood pressure tests when most doctors consider one to be sufficient? Because the readings in your two arms might be different. A few points' difference is normal. But a difference of 10 points or more in either the "top" (systolic) number or the "bottom" (diastolic) one could signal an underlying problem that might otherwise go undetected.

What kind of problem? In younger people, it might mean that one of your arteries is being squeezed, perhaps by a muscle. In older people, it likely means that one or more of your arteries are blocked, meaning you are at greater risk for heart disease, stroke, and dementia, among other things.

Five years ago, researchers in the U.K. found that a 15-point difference in the top number between arms could translate into a 70 percent greater likelihood of dying from cardiovascular disease. Since then, some European nations and some medical organizations in the U.S. have added both-arm-testing to their guidelines, but it's still rare for any nurse or doctor to actually do it. Most seem unaware of the significance that different readings between the two arms could carry.

Having read about the U.K. study a few years back, I've been asking for two arm readings whenever I encounter a routine blood pressure check. It usually seems like an unexpected request, but it's always granted, and usually adds about 30 seconds to the time it takes to give me the exam. I believe those 30 seconds are very well spent. You never know what you might find.