The tilt table will make you pass out at a certain time. You might be able to have the test without an iv. I have had one with and one without. You also don't have to pass out from the tilt table. They watch your vitals and you would have consistent elevations in heart rate and a drop in BP. You also can have a negative tilt and still have pots.

Those symptoms sound like they could be autonomic dysfunction for sure, glad you're getting evaluated so you can get some answers! I feel like passing out in a clinic is actually the safest place to do it lol and it isn't uncommon to do so during this test because of the blood flow changes. If you tell them you are nervous about the test, I'm sure they will be able to help soothe you as well as take that into consideration with the test results. I think it's perfectly normal to be anxious about such a physically taxing test. Just know the medical staff have conducted it before on others and most likely have a good idea of how to take care of you Also, its worth noting that POTS is only one type of dysautonomia and even if your tilt table test comes back negative, you could still be experiencing a different sort of autonomic dysfunction. For example, my heart rate doesn't meet the change requirements for POTS but I still have the symptoms you're describing and more (except mine is pre-syncope) so I carry a general diagnosis of dysautonomia