Question: I enjoy your column and try to read it every day. I have borderline high blood pressure but I’m not yet being medicated for it. I have noticed that the systolic (the upper number) blood pressure readings in my right arm are about 10 points higher than in my left arm. Is there any reason to be concerned about this?

Dr. Hibberd's answer:
Generally, a small difference in blood pressure readings between arms isn't a health concern. However, a difference of more than 20 millimeters of mercury (mm Hg) for systolic pressure (top number) or more than 10 mm Hg for diastolic pressure (bottom number) may be a sign of an underlying problem — such as narrowing of the main arteries to that arm.
A large difference in blood pressure measurements between your arms could signal a health problem, such as blocked arteries in your arms (peripheral artery disease), kidney disease, diabetes, or even heart defects. Your doctor may measure your blood pressure in both arms to see if you have high blood pressure (hypertension). If your blood pressure is higher in one arm, your doctor will probably use the blood pressure reading from that arm to monitor your blood pressure.