Paradoxically lower recumbant than sitting blood pressure reading

It is physiologically normal to find a difference in BP reading between the sitting and recumbent position. The recumbent systole is more than the sitting systole by usually a net 10mmHg.

In my general internal medicine clinic I usually have ~50% of cases having HT, about 10% of these have a recumbent BP reading lower than the sitting one, what I call a reversed response to gravity or body position.

This was found to have no relation to whether the patient is diabetic or not and is frequently found in hyertensive or normotensive patient not using any blood pressure lowering medication.

This phenomenon is related to a positive family history of HT even if the patient is not hypertensive himself at the time of consultation.

This normotensive cases of paradoxical BP reading may be more susceptible to develop HT in the future than those with a family history of HT but no paradoxical BP reading phenomenon.

The blood pressure should always be measured in the sitting left arm and the recumbent right one for every patient (right and left would make it less likely to miss this phenomenon)