Blood pressure is a measurement of the force exerted by circulating blood against the walls of your arteries. This force is expressed as two numbers, measured in millimeters of mercury (mmHg). The top number, known as systolic pressure, reflects the pressure in your arteries when your heart beats and pumps blood out. The bottom number, or diastolic pressure, indicates the pressure in your arteries between heartbeats, when your heart is at rest and filling with blood. Understanding these two values provides insight into your cardiovascular well-being.
Classifying a 138/71 Reading
A 138/71 mmHg blood pressure reading falls into specific categories based on established guidelines. According to the American Heart Association (AHA) and American College of Cardiology (ACC), a systolic pressure of 138 mmHg falls into “Stage 1 Hypertension.” This classification applies when systolic pressure consistently ranges from 130 to 139 mmHg.
Conversely, a diastolic pressure of 71 mmHg is “Normal” (less than 80 mmHg). When systolic pressure is elevated (130 mmHg or higher) and diastolic pressure remains healthy (less than 80 mmHg), it’s called “isolated systolic hypertension.” This is common, especially among older individuals. A high blood pressure diagnosis typically relies on the average of multiple readings taken on separate occasions, not a single measurement.
Potential Causes for an Elevated Systolic Reading
A single elevated blood pressure reading, like 138/71 mmHg, can be influenced by temporary factors, not necessarily a chronic condition. Emotional states like stress or anxiety can cause a temporary increase, sometimes called “white coat hypertension” in a clinical setting. This response can elevate readings by as much as 15 points.
Stimulants like caffeine or alcohol can temporarily raise blood pressure, sometimes for 30 minutes or more. Physical exertion before a measurement, like rushing, increases heart rate and blood flow, leading to higher readings. Even a full bladder can elevate systolic pressure by 10 to 15 mmHg due to sympathetic nervous system activation.
Improper measurement technique is another common cause of inaccurate readings. A blood pressure cuff too small for the arm can falsely increase systolic readings by 10 to 40 mmHg. Placing the cuff over clothing can also impact systolic pressure by 10 to 50 mmHg. Talking during a measurement or having unsupported feet or back can also contribute to temporarily higher readings.
Actionable Steps After a High Reading
An elevated blood pressure reading should not immediately cause alarm, as a single measurement may not represent your usual blood pressure. Relax for three to five minutes before taking a reading, seated comfortably with your back supported and feet flat on the floor. Your arm should be supported at heart level, and the cuff should be placed directly on your bare skin, not over clothing.
For accuracy, take two to three readings each time, waiting one to two minutes between measurements. Keep a detailed log of readings over several days, noting the time and any influencing factors, to provide a comprehensive picture for your healthcare provider. Consistently high readings over a week warrant a discussion with a healthcare professional to determine the underlying cause and appropriate management plan.