I have had orthostatic intolerance for a couple years but have yet been able to prove it on a tilt table test. I have had two tests and both are negative. Does anyone else have this problem? I'm trying to prove it for my disability case. My CFS doctor said it is obvious that my HPA is unbalanced and that it just may not be happening all the time. Does anyone know of any other tests that I could have performed at a doctor's office that would show autonomic dysfunction of any kind?