How High Is Too High for Blood Pressure? Doctor Warns About 'This Number' and Why One-Time Measurement Is Wrong

Endocrinology and metabolism specialist Dr. Tsai Ming-Chieh explained on his Facebook page 'Dr. Tsai Ming-Chieh – Health & Weight Loss' that according to the Taiwan Heart Association and current clinical guidelines, a blood pressure reading below 120 mmHg systolic and below 80 mmHg diastolic is considered within the normal range. If systolic pressure is between 120 and 129 mmHg while diastolic remains below 80 mmHg, this is classified as elevated blood pressure, also seen as a precursor to hypertension. At this stage, immediate medication is usually not required; instead, lifestyle adjustments can be made to bring blood pressure back to normal levels. Hypertension is diagnosed when systolic pressure reaches 130 mmHg or higher, or diastolic pressure reaches 80 mmHg or higher.

Dr. Tsai warns that a single high reading does not automatically mean a person has hypertension. Some individuals experience heightened sympathetic nervous system activity due to anxiety when entering a medical facility or seeing a doctor, causing a temporary spike in blood pressure. This phenomenon is known as 'white coat hypertension' and cannot be controlled simply by willpower. Prescribing antihypertensive medication based solely on one high reading in a clinical setting could lead to the risk of excessively low blood pressure at home due to overmedication. Therefore, home blood pressure monitoring records are crucial for understanding a person's typical blood pressure status.

The Department of Health's Health Promotion Administration and the Taiwan Hypertension Society recommend following the '722 Rule' for home blood pressure monitoring. '7' means measuring for seven consecutive days; the first '2' means measuring once in the morning and once in the evening each day; the second '2' means taking two consecutive readings at each session, with a one-minute interval, then averaging the two values.

Following this method consistently helps obtain a more reliable average home blood pressure value over the week.

Morning measurements should be taken within one hour of waking, after using the bathroom, and before eating breakfast or taking any medication. Evening measurements can be done within one hour before preparing for bedtime.

Thirty minutes before measurement, avoid smoking, eating, consuming caffeine or alcohol, bathing, or engaging in vigorous exercise. Before starting, empty your bladder and sit quietly for five minutes.

During measurement, sit on a chair with a backrest, keep your back supported, and place both feet flat on the floor without crossing your legs or sitting cross-legged. Wear loose clothing; if wearing long sleeves, it's better to remove the sleeve rather than tightly rolling it up, which may compress the arm. Rest your arm naturally on a table, ensuring the center of the blood pressure cuff is approximately at heart level. Stay relaxed during measurement, avoid talking, and do not move your body.

After completing seven days of monitoring, calculate the overall average blood pressure. A physician will consider a diagnosis of hypertension if the average systolic pressure is 130 mmHg or higher, or the average diastolic pressure is 80 mmHg or higher.