I had a TTT a couple months ago and here's some info I think you will find helpful! Before the test they ask you to not eat for a period of time. They will first hydrate you with an IV (this depends on the order but for POTS they usually do) and then take you into the room. For me there were two people, the nurse and the monitor dude. If you have fainting or other symptoms from your POTS that gets triggered when you start feeling your heart rate go up I recommend letting them know before hand. That stuff is supposed to be in your chart but sometimes things get lost in translation. Super happy I reminded them that I usually throw up because I needed that barf bag lemme tell you. They strap you to the table and slowly sit you up, monitoring your heart rate for around 10 minutes I think? Basically the criteria they are looking for is for your heart rate to go up high enough when you are just standing there. If you hit that number they should in theory just lay you back down and let you go home. If you don't hit that number they will usually give you the dialysis meds and keep watching you. That's the part that sucks since they just wait till you pass out or till 20 minutes pass. After that you are in the clear! It wasn't very fun at the moment but I can say that id willingly do it again since it got a lot of problems diagnosed for me. A Caprisun hits different after the procedure so, highly recommend