I'm trying to make sense of this blood volume thing. But to do this I have to read more into it than he said. Anyway, here's what I get from him and what I read into it.
We have low blood volume (idiopathic hypovolemia). But because we also have Systemic Basal Constriction, our blood pressure doesn't drop to a corresponding level. I'm not sure what Systemic Basal Constriction means, and I can't find it with Google. So I'm going to guess is means system-wide constriction of the vascular system. This could be caused by isoprostanes, which can result from oxidative stress. Or, at least, I think he mentioned oxidative stress. But regardless of this, our lower blood volume doesn't show up in routine blood tests because they test the density of blood cells within whole blood, not the total volume of whole blood. Anyway, because we have less blood flowing through us the services provided by blood circulation are diminished. One of these services is delivery of oxygen to cells. So we have less oxygen getting round there in general. But here's what I don't get. How does this all cause orthostatic intolerance. If the vascular constriction is raising blood pressure to compensate for low blood volume, why does it get worse when we stand up? We should feel equally dizzy all the time. But some how blood pools in our lower areas despite compensation by the vascular system. Unless, maybe, there is just not enough blood to keep it distributed despite vascular constriction. Or to put it another way, if there were a way to take the blood pressure in our heads versus our arms, it would be much lower in hour heads.
Sounds good to me. But sometimes a dish of beans sounds good. I wish I could ask Dr. Bell to comment on this.
BTW, while writing this whole thing a light bulb went off in my head. Immune cell tests assume a normal amount of blood. IOW, when they tell us the number of NK cells, they are basing this on the density of NK cells in the blood sample. If we have 1/3 less blood, that means we might have 1/3 fewer NK cells than people with the same score and a normal blood volume. This could tip the scale from us having minor immune problem readings to major immune problem readings. Of course, I imagine human physiology is not that simple. But I think this is worth pondering.