Were the bags they gave you the lactated Ringer's solution? I think that's fairly standard. It's supposed to be like blood in its concentrations of solutes (electrolytes?). Which means it has sodium, yes, but also potassium. Still, it probably moves your blood generally closer to being in the right balance.
Low aldosterone makes you lose salt. cortisol shunt gives you low aldosterone. Hyperactive HPA results in cortisol shunt.
I've found that licorice helps me a lot. It eases the effects of cortisol shunt and that seems to allow my body to build up aldosterone, let alone the other hormones that were getting robbed by cortisol production, and I feel much better.