What does the test diagnose and what is the benefit of having it diagnosed?
The tilt table test is used to diagnose different types of Orthostatic Intolerance (OI). Just off the top of my head I can think of three main benefits:
1. In my case a diagnosis of a type of OI (Neurally Mediated Hypotension) explained most of my symptoms. I had been describing what seemed to be a set of unrelated symptoms to my doctors for years. But because I never fainted (I got lots of pre-syncope symptoms) no one ever suspected that these symptoms were due to OI. It used to be that doctors only suspected OI problems if the patient fainted. Doctors now know (or they
should know) that there are different types of OI and many ME/CFS patients who have OI do not faint (although, of course, some of them do faint).
Knowing about this problem helped me to avoid situations that trigger NMH symptoms. It also led me to try various treatments (here's one list -
http://www.dinet.org/what_helps.htm and here's another one -
http://www.medhelp.org/health_pages/Neurological-Disorders/Dysautonomia-Treatments/show/171?cid=196 ) in order to manage the condition.
2. The abnormal results from a tilt table test can be used as objective evidence for long term disability. In the USA that generally means social security disability benefits but may also mean privately purchased LTD or even ERISA LTD. I don't know what the long term disability situation is like in other countries.
3. A third benefit, perhaps less tangible to many but still quite real, is validation. I had a wonderful husband who always believed in me. And my primary care physician had no idea what was wrong before the tilt table test but she did believe that I had a real illness. (I had "fired" a bunch of other doctors before I found her in 1994 and I'm still with her today). But still, just knowing that all those weird symptoms were connected, and could be measured and documented, was helpful.
I can only imagine how much more helpful an abnormal test result is when all your family, and even your doctors, think that "you're oversensitive" or "you're imagining things" or "you could do it if only you'd try harder." I read these kind of stories on forums like this all the time - it's heartbreaking. Any validation is helpful in these horrible situations.
I mean if there is no accepted treatment for it (like a benefit in insurance coverage or something) then what good is it? Just wondered.
I'm unsure why you think there's no accepted treatment but perhaps I misunderstood you? There are lots of possible treatments but, like most chronic illness, there's no guarantee that what works for one patient will work for another. Some patients have a lot of trouble finding anything, whether it be prescription drug or supplements, that helps them manage their OI symptoms. I'm lucky in that I have found a few prescriptions that help me (not a cure, but a help). All my prescriptions are covered by my Medicare drug Part D coverage (part of a supplemental Medicare plan).
rydra_wong, for a general overview of Orthostatic Intolerance here's a short web page -
http://www.cfids.org/about-cfids/orthostatic-intolerance.asp
For a longer description try the Johns Hopkins document here -
http://www.cfids.org/webinar/cfsinfo2010.pdf
There's lots of information out there on the web but these are good places to start.
I have heard that some doctors are willing to give a tentative diagnosis of Orthostatic Intolerance without the tilt table test if the patient has lots of symptoms that match up with that diagnosis. Then they work with patients and have them try different treatments to see whether they help. The only problem with this approach is that if the treatment(s) fail then it's not as clear whether the diagnosis was wrong or whether patient didn't respond to those particular treatments. But it is cheaper and easier for the patient if they can avoid a tilt table test because it's certainly no fun. (it took me a week to recover from my first test)
Edited - PS to taniaaust1, I hope you find a clinic or hospital that will do your tilt table test for you. You said the cardiologists you saw had never heard of POTS. Have you tried showing them the document from Johns Hopkins? It might not work but at least it's worth a shot.