Happy holidays, everyone!
Just thought I'd chime in. I was initially diagnosed with POTS via a tilt table test (TTT) two and a half years ago when my symptoms became debilitating. Symptoms continued to worsen over several months, so I went for a week's worth of testing at Mayo Clinic - Rochester. There, I was diagnosed with hyperadrenergic POTS (my standing norepinephrine was close to 1000), neuropathy, hypervigilant state (hahaha...that one was because sounds and movement triggered sx). Since then, I've been diagnosed with many environmental allergies and migraine.
I tried all the recommended treatments for H POTS and none helped, except mild-moderate exercise (strenuous exercise exacerbated symptoms). Some meds (beta blockers) made me worse. Over time, I also became more aware that quite a few of my symptoms (e.g., itchy rash, throat swelling, sound sensitivity) did not fit with POTS and it was clear to me that something other than hypervigilance was making me symptomatic.
Last summer, I saw Dr Afrin and was diagnosed with MCAS. He seemed to believe that my POTS symptoms (as well as all my other sx) are a result of mast cell degranulation. There are over 200 mast cell mediators that can be released from mast cells, with histamine being one of them. There are plenty of mediators that can cause autonomic nervous system problems associated with POTS.
Like many other POTSies, I experience increased symptoms sitting and especially when standing. Those are but two of the multitude of triggers I have identified so far. After viewing my POTS symptoms through the lens of MCAS, I have come to see them as MCAS symptoms, themselves.
Here's why I think my POTS symptoms are part of my MCAS - 1) The many, many POTS meds and behavioral changes I tried didn't work. 2) Beta blockers made me worse. They are known MC degranulators. 3) Strenuous exercise - another MC degranulator - increased my sx. 4) H1 and H2 blockers have helped with many of my POTS sx, including blood pooling in my legs. I was able to stop wearing compression hose after starting antihistamines! 5) Gastrocrom is beginning to help with some of my POTS sx.
In the report from my visit, Dr Afrin explained that it is extremely unlikely that I would be so special as to have multisystem polymorbidity and various causes to explain them. In other words, what are the chances that I have POTS, migraine, neuropathy, allergies to nearly everything in the world, etc? It is much more likely that I have one problem happening that is causing these symptoms across systems in my body. It sure was nice to have someone tell me I'm not special!
So, in my case, at least, the evidence is there to support MCAS as my diagnosis - and all my other diagnoses (POTS, migraine, neuropathy, "allergies") as symptoms of MCAS.