I agree that you should find a good endocrinologist. In addition to rechecking the thyroid levels, I would definitely have him check your adrenal function. In Hyperadrenergic POTS, adrenaline production is always on…so in between episodes the adrenal gland experiences fatigue because your body lives in a constant state of overstimulation. I would also request him to order a supine and standing norepinephrine test…if your norep increases dramatically from lying to standing then a diagnosis of Hyperadrenergic POTS can be made. We are currently scheduled to see my daughter’s endocrinologist…because it is my hope that she can address the adrenaline surges by suppression medication that will address the adrenaline production which should help all of my daughter’s issues and not just the elevated heart rate. We are also going to have her rule out pheochromocytoma/paraganglioma (type of tumor that secretes catecholamines) because Hyperadrenergic POTS can mimic such a tumor. The symptoms are very similar, because they both oversecrete adrenaline, but they have different causes. If you have Ehlers Danlos as your primary disease then your adrenaline secretion is most likely due to Hyperadrenergic POTS and not a tumor. But I think its worth ruling out.