I had been diagnosed with POTS. They did heart monitoring and a tilt table test to diagnose. God has given me the ability; however, to correct POTS through nutrition and I no longer have the heart palpitations or racing heart upon standing. My MD is amazed and recommending people do the same things as I did. Of course, another MD is trying to say I was misdiagnosed now that my symptoms are gone, but I fully believe, after researching it, our bodies can heal themselves given the right fuel. I am no longer on beta blockers or xanax. No prescription meds at all! Yeah!
I will be glad to share with anyone my journey and all the things I did to correct POTS...just email me.....
I'm still not 100% yet, so this is probably a less comprehensive answer than I would normally give, but here's what I've got. From what I see in Dr. Grubb's medical textbook, Syncope: Mechanisms and Management, upright serum norepinephrine levels of >600 ng mL in combination with symptoms that point more to H-POTS than PD would be the diagnostic criteria (2005, p.231).
Keep in mind (I know, I've beaten this poor horse to death and beyond), though, that the entire concept of the distinction of dividing pots into these two categories has still not gained universal acceptance. The flow model is a different way of looking at classifying different cases of pots. NET deficiency has accounted for a small number of patients. As POTS is researched further, these various explanations and models will be refined and possibly combined.
"Very carefully."
Sorry, bad joke. That's a great question. I wonder the same myself. Is it a higher level of catecholamines upon standing (or in general) perhaps? I'm not sure.