Hello helpforthecure, First off, let me say I am NOT a physician, but I have a degree in clinical laboratory science and run lab work daily so I have a little knowledge on the subject. Low potassium can be caused by dehydration. People with dysautonomia have a low blood volume, which means we are basically chronically dehydrated so it could very well cause your potassium to drop. Also, POTS isn't necessarily based on your blood pressure. It used to be called orthostatic hypotension because it was originally thought that only the blood pressure was affected but was changed to POTS (postural orthastatic tachycardia syndrome) because it was discovered that a lot of the symptoms were actually caused by an increase in heart rate when standing. I have been extremely active all of my life and have always done intense workout programs, but I often find myself out of breath or that my heart is racing just from doing very simple tasks. So your symptoms very well could be from the dysautonomia since they've done all the cardiac testing and can't find anything directly related to your heart. However, like I said, I'm not a doctor so don't take my word as gold, but hopefully you can find a little solace in the fact that you are not alone in your symptoms. Hope this helps!!