Dear Dr. @Kamal Chémali,I don't think we understand the pathophysiology of POTS well enough to comprehensively answer this question.There are a number of technical issues that come into play when drawing serum catecholamines.First of all, many things can elevate catecholamines temporarily: ex...

I agree with Dr. @Nathaniel Robbins. Let me add 2 things: I believe it was implied, but let’s be clear that when we are talking about excessive catecholamines, we are talking about the ratio of the standing to the lying norepinephrine values, not absolute values. We can classify that easily i...