Postural Orthostatic Tachycardia Syndrome Please Help

How is postural orthostatic tachycardia syndrome diagnosed? I know that it can be very serious debilitating disease and that is not easily diagnosed. I think that my husband could have it; he was misdiagnosed with anxiety disorder which was nonsense. He has typical orthostatic hypotension symptoms, like light-headedness, increased heart rate upon standing, headache, nausea and impaired concentration.

Postural orthostatic tachycardia syndrome is often difficult to diagnose and is sometimes misdiagnosed with anxiety disorder or panic attacks. Test that is vital for diagnosing POTS is tilt table test. Blood test is done to verify level of norepinephrine that is usually abnormally high in patients with POTS. But test to rule out phochromocytoma is also needed.