This common mistake can add nearly 7 points to your blood pressure reading

A Johns Hopkins Medicine-led study suggests that the way a patient positions their arm during a blood pressure (BP) check can meaningfully affect the result. Common arm positions used during screenings may make blood pressure appear higher than it actually is, potentially contributing to an incorrect diagnosis of hypertension.

In a report on the study, published in JAMA Internal Medicine , researchers compared three arm positions: an arm supported on a desk, an arm supported on a lap, and an unsupported arm hanging at the patient's side. They found that resting the arm on the lap increased systolic pressure (the top number in a BP reading) by nearly 4 mmHg, while allowing the arm to hang unsupported at the side increased systolic pressure by nearly 7 mmHg.