Why Is the Blood Pressure of One Arm More Than the Other?

Greater use of one arm can cause variations in artery wall thickness between arms, commonly resulting in slightly higher blood pressure readings for the dominant arm. According to the American Heart Association, the dominant arm can register up to a 10 mm Hg higher difference in the systolic reading for blood pressure than the other arm.

The Dominant Arm

• The dominant arm---for example, the right arm in right-handed people---develops differently in most people than the less-dominant arm because of higher overall use. Variations in the dominant arm can include smoother, more trained muscle fibers that may lead to slightly increased artery wall thickness in the arm.

Arteries in the Arm

• Arteries in the dominant arm may stretch more easily to allow better blood flow regardless of the increased artery wall thickness. The medically accepted 10 mm Hg higher systolic blood pressure reading in the dominant arm when compared with readings from the nondominant arm is linked to typical physical differences between arms.

Blood Pressure Readings

• Normal blood pressure readings typically fall at or below 120 for systolic and 80 for diastolic pressure. Systolic readings consistently higher in one arm by more than 10 mm Hg may indicate a chronic heart condition.

Checking Both Arms

• Taking blood pressure readings in only one arm may mask underlying heart disease. The American Heart Association recommends taking blood pressure readings in both arms and using the arm that consistently registers higher readings for diagnosis of any heart condition.

When to See a Doctor

• Differences in blood pressure readings between arms may indicate hypertension or other heart conditions. Schedule a consultation with a physician if self-monitored blood pressure readings significantly differ from those taken by health care professionals. In addition, see a doctor if systolic readings differ by more than 10 mm Hg between arms.