How do you know if its postural orthostatic tachycardia syndrome or cardiac autonomic neuropathy? male 22. not diabetic. thanks

Here's my take: Postural orthostatic techycardia syndrome is fairly common and has a variety of different causes if the pathologist gets to look at nerve. Since you're asking to distinguish two not-well-understood illnesses, neither of which has a specific treatment, and since autonomic neuropathy is usually a diabetic's problem, i'd go with the good clinical fit -- if it seems like pots, then that's working dx.