I have no idea what is causing my orthostatic problems. And I completely agree that extra salt and water is a short term solution (and it only helps bit, nowhere near a cure). It's sort of like how it's easier for me to do things on an empty stomach, or when it's cold. It doesn't make my ability to stand still go back to normal. It just makes things that are very difficult a little bit less so.
+1
(Though I do things better after eating a small meal and when the temperature is moderate)
There is also the problem, as I see it, that in the USA virtually all clinical practice is for profit. Prior to joining in ME websites I had little information on what went on in US practice as compared to the UK. Having 'listened in' for four years it seems to me very clear that a lot of unproven treatments are offered to patients as 'mainstream' I the USA. In the UK doctors are mostly paid to do whatever work comes along and have no incentive to see more patients. So these treatments are not considered mainstream in the UK. The downside here is that there is not enough funding even to give people the mainstream treatments, but that is another issue.
There are some problems with the U.S. system, but doctors very seldom make money from prescribing medication (they write a script and fax it to a pharmacy of the patient’s choice, which is usually a completely separate company). Usually not making money from prescribing tests, either (maybe possibly in a physician-owned clinic, they might make money from MRI or botox or something, but that type of clinic is super rare—and that still wouldn’t apply to blood tests, which will generally be sent to a lab someplace else).
The for-profit system mostly tends to stress the doctors (as they have to spend a lot of time getting pre-authorizations, and see too many patients, and be careful not see a lot of Medicaid patients), and limit tests and medications (particularly expensive ones, but it will also shift prescribing to whatever type of medication is covered by the patient’s insurance—unless the doctor is working for an HMO, this has nothing to do with the doctor or the doctor’s workplace, although the plan might have been selected by the patient’s workplace).
The doctors that are doing the kinds of things you say would be mostly the alternative ones (e.g. ND), who tend to sell a lot of herbs and things directly from their clinic.
But the dysautonomia docs? No. As far as I can tell, they are not making money from making one recommendation over another.
This hype over fee for service causing overtreatment is only hype. I read an overview of a study showing U.S. patients go to the doctor less, stay in the hospital fewer days, and get less or no more treatment than people in similar countries. Just each thing costs more here (but it’s the pharmaceutical companies, the pharmacy benefit managers, and the hospitals making the money in general, not so much doctors). (Not to say another way might not be as good or better, just there’s no evidence this way is causing that particular thing.)
The only problem that anyone I know can think of with blood shifting on standing is that there is not enough getting to the top (brain). And we are all familiar with feeling faint and we know that is due to not enough blood getting to the brain via arteries. The only reason for not getting enough arterial blood to the brain is a low systolic blood pressure (you need to pump at least a foot so you need enough pressure).
This all makes sense for orthostatic hypotension (=low pressure) with the symptom of feeling faint on standing.
But the review you quoted says something strange about POTS. It says that the pressure does not fall, just that the heart rate goes up. Moreover, to be POTS the rise in heart rate must be associated with symptoms. But what symptoms? He does not say. If the pressure is OK there should be no faintness. The rapid heart beat might seem disconcerting but in itself it is something we are all happy about when we exercise. It should not be something that requires medical treatment. So what is it that people with POTS complain of? I realise that I do not know.
As best as I understand it, the theory with the rapid heart rate is that it’s preventing a drop in blood pressure. (And this is what my cardiologist told me, if I recall correctly.)
As for low blood volume, that’s pretty apparent from pulse pressure, though there’s also a fancy test where they put a nuclear marker in your blood to check the volume and other things.
https://www.sciencedirect.com/science/article/pii/B9780323392761000172 (I can see the overview but it does seem to introduce pulse pressure)
https://my.clevelandclinic.org/health/diagnostics/16793-blood-volume-testing
As for sodium and potassium, do have a look into the “renin-angiotensin-aldosterone system.”
Interestingly enough, cAMP comes up. Also histamine.
http://www.urology-textbook.com/kidney-renin-aldosterone.html
For a definition of dysautonomia and a description of prevalence,
https://my.clevelandclinic.org/health/articles/6004-dysautonomia
Basically it’s a lot like Raynauds: a description of a specific set of signs and symptoms that might be primary or secondary and have various causes, but similar ways to relieve symptoms. Actual cures would depend on cause.
My problem is, I have no idea what my pulse rate did when I was healthy, so I don't know to what extent this sort of result is a signal of disorder. Maybe I should test a few healthy friends of my age and gender to see what their pulse rates do in parallel circumstances!
I’ve heard of otherwise healthy people sent to ER for having heart rates that were high while at rest.
Sorry for the massively long post.