Why my blood pressure changes from sitting to standing

[greece7]

My blood pressure changes from sitting to standing possition. When I sit I feel like fainting. Measurement are:
1. Sitting: High blood pressure is 103 and the low one is 55. Heart rate is 66
2. Standing: High blood pressure is 112 and the low one is 73. Heart rate is 67

Can somebody tell me what should I be looking for with doctors

[grendslori]

Another thing that you need to consider is home BP units are not really the best monitors of blood pressure and pulses. The only time the is a variation in BP where you would need to be concerned is when there is a 20 point difference; your BP has a 9 point difference only. If that is the case, then you are considered dehydrated. Your BP is a bit low when sitting, and even when standing, but are still in a 'normal' range for most people. If you are continueing to get dizzy, see you doctor and let him determine if this is a problem.

[ellex]

Your heart rate is normal. and blood pressure is suppose to change, with movement and activity. your sitting bp is a little low, but not something to really worry about unless that is what it is when you are active. you probably feel like fainting because you may not be getting enough oxygen and blood flow when while you move from standing position to sitting.  Im not a doc but try drinking a lot more water and caffeinated drinks and see if that changes your bp or how you feel when you sit.

(Im a patient care tech at a hospital)