Q: I have hypertension for 15 years. BP is high (about 150/100) when measured sitting up, but normal (< 140/90) laying down, measured within minutes. It has been this way all along. My doctor’s answer does not sound very unconvincing, and I just want to know more about the big difference.
A: Blood pressure measurement varies with position. It is harder for your heart to get blood to your head when you are sitting. Your heart is a pump. In the upright position, the heart has to pump uphill because your head is located at a higher level than your heart. When lying down, your heart and your head are at the same level. Your heart does not need to pump as hard so your blood pressure is lower. By medical convention, blood pressure is measured in the sitting position. Calculations of blood pressure are standardized to this position. It is well known that blood pressure is lower in other positions but to determine the need for treatment the seated position is used. In other words, to make a treatment determination in a non-emergency situation, your doctor should use the blood pressure taken while you are sitting.
Sitting vs Standing Blood Pressure Measurement