I understand that a POTS diagnosis is one of the most simple and clearcut medical tests you can get: if your heart rate increases by at least 30 points on becoming upright from a relaxed lying down conditions, then you have POTS. Simple as that.
Are you saying that there are some POTS-like syndromes which also satisfy this 30 point increase, but which are not POTS?
No, POTS is right now defined as +30 average increase without any drop of BP.
I can't know this, but I know as mentioend people misdiagnoed w POTS because they have similar condition like increase of HR initially but then it falls back , and on average wasnt +30, they still got diagnosed because doctors weren't pots specialists (As there are few).. and such person didnt have positive antibodies either
another reason would be if tilt up test is not appropriate for autonomic testing, like in some cardiology units, and doesn't measure BP frequently enough.
i think Initial Orthostatic Hypotension can be detected only w tilt test that measures BP from finger too, -and IOH would produce initial spike in HR
I think the answer is in between. I have an official diagnosis of POTS confirmed by 2 tilt table tests (and other such tests).
I have been ill for 9 years, and I have experienced autonomic symptoms that entire time. (Gastroparesis, heart pounding, little to no sweat, etc). However I only experienced the tachycardia aspect of POTS for around 2 years when I was at my very worst.
Now I would probably pass a tilt table test as normal as my HR seems to have become more undercontrol. However if I have a bad day, or it's too warm, or I have just eaten, etc I would probably fail the tilt table again.
I still have all the autonomic symptoms I have had from the start, my heart pounding is still my worst symptom, heat, food, carbs, exacerbate my condition; however I would probably be declared in remission if my POTS docs gave me another TTT.
So I think POTS is certainitly a thing and is somewhat useful as a diagnosis however it's not a you either have it or you don't sort of thing, more of a spectrum. I hope that makes sense.
This is different because you already had clear positive TTT, so there is no question you have it. It's like MS, they can have 1 positive MR and later long period of remission, they still have MS.
of course TTT is not perfect.
I had 3 positives nonstop all bookcase, after IVIG my TTT got negative because my antibodies reduced drastically and overall my OI was less present, but I still have POTS, just less active.
Important for diagnosis is that that one time you had positive TTT it was properly done, of course.
Of course there ae many conditions in between, that's what I am saying, some of them are not autoimmune.
My TTT also got much much worse when the lab had heating issue and it was +40 C in lab I was laying on table 1+ hr, i boiled, and the results were extreme. Heat is most common trigger for me.
My POTS is exclusively orthostatic intolerance, I dont have any gastro or urinary issues, not even sweating, palpitations, dizziness. I don't feel my Heart beat even when I have 150-160 HR, .. i just feel OI and fatigue until i lay down.