How is Dysautonomia / POTS diagnosed?

Autonomic Testing
Orthostatic Testing
Tilt-Table Test

Cardiology
Electrophysiology
Primary Care Physician

I believe that the TTT or Tilt Table Test is the best ways to diagnose POTS. Along with that, the sweat Test is taken.

Tilt table, cardiac monitor

Usually with a tilt table test

Usually people are diagnosed by a tilt table test where you sit lay & stand, they see what your blood pressure does

Typically with a TTT (tilt table test)

Poor man's tilt table test/collection of symptoms and monitoring your pulse --> autonomic tilt table test

As it is a 'Syndrome' rather than a 'disease' - there is no 'blood test' or MRI that can be done and say 'oh yeh - look at that point there - that says its POTS' it is difficult.
A collection of symptoms, a holter monitor test, a tilt table test if it is available (on occasion there is no need for a tilt table test and on occasion you will have a patient who is a little large for the tilt table at that particular hospital or one is not available - if everything else matches up and in particular if the patient has passed out or just about passed out in front of them on changing position, standing up etc and their BP and HR has been observed, and on occasion the Holter Monitor will provide enough information. Loved ones/Carers who can back up what they have observed can also be helpful in diagnosing as well.
Generally a General Practitioner will send the patient to a Cardiologist who will do the testing and collect data and make an informed decision.
I encourage anyone who has POTS or suspects POTS to keep a diary over the space of a month with ALL symptoms, no matter how big or small, how they have felt, how dizzy they have been, any passing out, or near passing out, what was going on at the time, what foods/drinks they changed, how hydrated they were at the time....
Hydration is important as well - KEEP hydrated.... keep the salt intake up a little as well so electrolyte drinks are fabulous - NOT energy drinks - they wont do the heart rate any good.... but keep a complex food diary, mood diary, symptoms etc..... go in armed with that info to the doc and if you have a heart rate monitor - keep a record and times etc - a BP monitor is handy - either buy or borrow one.....
THeres no point getting an appointment with a cardiologist and having to go back in a month because they want all that info or you sit there going 'um...... yeh I guess so' ... it just wastes everyones time.