@cfs since 1998 , any combination is possible until there’s research to pin it down – autonomic problems cause chronic low blood volume, chronic low blood volume causes autonomic problems, or both are caused by a third factor.
A couple of studies in OI and in CFS have found something amiss with the functioning of the renin–angiotensin–aldosterone system (RAAS), which regulates blood volume.
We don’t know exactly when the blood volume declines, because blood volume isn’t regularly measured. Also, people tend not to see an autonomic specialist until they have been unwell for some time, so even if the specialist orders a measurement it will be months or years after onset. And then there’s the 10% of people with CFS who don’t have low blood volume.
The decrease in blood volume is fairly small, so it’s unlikely you would notice it. Also, it may not be a matter of suddenly losing it, more that your body no longer tries to top up to 100%.
Until you can get your blood volume measured and find out whether it is low or not (will be more accessible soon), it might be best to avoid diuretics. Even otherwise healthy people report feeling faint and unwell on spironolactone, and they are presumably starting with normal blood volume. And we do know that low blood volume causes transient orthostatic intolerance symptoms (has been studied at NASA). But inducing low blood volume doesn’t cause an orthostatic intolerance syndrome (such as POTS), nor does it make the RAAS malfunction, so there must be more too it.
New techology to quickly and inexpensively measure blood volume:
https://detalo-health.com/
I spent *forever* investigating and treating low blood volume – everyone thought I had it. Turns out I didn’t! Wish I could have been checked with the above gadget on Day One. I lost about 1.5 years to a red herring.
A couple of studies in OI and in CFS have found something amiss with the functioning of the renin–angiotensin–aldosterone system (RAAS), which regulates blood volume.
We don’t know exactly when the blood volume declines, because blood volume isn’t regularly measured. Also, people tend not to see an autonomic specialist until they have been unwell for some time, so even if the specialist orders a measurement it will be months or years after onset. And then there’s the 10% of people with CFS who don’t have low blood volume.
The decrease in blood volume is fairly small, so it’s unlikely you would notice it. Also, it may not be a matter of suddenly losing it, more that your body no longer tries to top up to 100%.
Until you can get your blood volume measured and find out whether it is low or not (will be more accessible soon), it might be best to avoid diuretics. Even otherwise healthy people report feeling faint and unwell on spironolactone, and they are presumably starting with normal blood volume. And we do know that low blood volume causes transient orthostatic intolerance symptoms (has been studied at NASA). But inducing low blood volume doesn’t cause an orthostatic intolerance syndrome (such as POTS), nor does it make the RAAS malfunction, so there must be more too it.
New techology to quickly and inexpensively measure blood volume:
https://detalo-health.com/
I spent *forever* investigating and treating low blood volume – everyone thought I had it. Turns out I didn’t! Wish I could have been checked with the above gadget on Day One. I lost about 1.5 years to a red herring.