A normal doctor's check-up typically involves basic medical routines like taking your blood pressure, which is usually done in one arm. But medical experts are now urging people to check blood pressure in both arms — the reading could be different between the two, which may signal some serious cardiovascular problems.

In a new study, researchers reviewed some 3,390 people who were over the age of 40 and who did not originally have cardiovascular disease. The authors followed them for about 13 years, and during this time, 598 of the participants had a first heart attack, stroke, or some other cardiovascular issue. The study found that over 25 percent of those 598 people had a different systolic blood pressure reading of 10 or greater between one arm and the other — meaning, in a nutshell, that their blood pressure was higher in one arm than in the other.

This difference of 10 or greater is actually a risk factor for a cardiac problem, the study’s authors argue. It raises the risk of a heart attack or other cardiovascular event by 38 percent, “even when the absolute difference in arm systolic blood pressure is modest,” the authors write.

According to the Harvard Health Blog, a difference in blood pressure between arms could be a sign of circulatory problems that may lead to peripheral artery disease or stroke. Another study conducted by British researchers found that people with an arm-to-arm difference of 15 or more were twice as likely to get peripheral artery disease, which involves clogged arteries that are in arms and legs, rather than the heart. The authors of the study emphasize the importance of checking both arms; they state it should be a part of routine medical care.

But don’t let a small difference of only a few points scare you. In fact, having a difference in blood pressure between your arms is typically quite normal, if it’s only a few points. When the difference is higher than 10 points, you should talk to your doctor. Typically, younger and healthy people may have a difference in blood pressure due to a muscle compressing an artery, or some structural problem, the Harvard Health Blog says. In people who are older, clogged arteries are usually the reason behind a significant difference.

To prevent a difference, the study’s lead author Ido Weinburg, an instructor in medicine at Harvard University, says there are a few things to keep in mind. “Relax before your blood pressure is taken,” Weinburg told The New York Times. “And have a measurement with several repetitions in each arm to see if there’s a difference.”

Source: Weinberg I, Gona P, O'Donnell C, et al. The Systolic Blood Pressure Difference Between Arms and Cardiovascular Disease in the Framingham Heart Study. The American Journal of Medicine. 2014.