Questus, I hope you'll share some of your hard-earned knowledge. Is the only way to diagnose hyperadrenergic POTS with a catecholamines test? I think my cardiologist is thinking that I may have hyperadrenergic POTS (tachycardia, substantial BP and HR increase on standing), but is checking first to see if increasing blood volume resolves my tachycardia. I'm wondering if I should just request a catecholamine test. Any thoughts?