I hadn't looked at low aldosterone levels as everything I have read (I haven't read everything!) says that people with MS have high cortisol and aldosterone, not low. As for adrenal insufficiency, I think it might be possible but I don't think it's likely our chronically elevated levels are high enough to burn out our adrenals. Perhaps that's why no one pays attention to our cortisol/aldo levels. From the outside, they don't appear to be causing much trouble. I did some digging though because you made me curious. Here's what I found...http://www.mdguidelines.com/aldosteronism
Aldosteronism may not cause symptoms that prompt an individual to see a physician. When symptoms are present, they relate directly to the actions of aldosterone. A low potassium level can cause overproduction of urine (polyuria), which results in excessive thirst (polydipsia) due to fluid loss. Too much potassium excreted in the urine causes tiredness, weakness, muscle cramps, muscle spasms, and headaches. Some individuals may experience heart palpitations, often described as a fluttering feeling in the chest. In severe cases, periods of paralysis or mood changes may be reported.
Sluggish blood flow? http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2842872/
All hypovolemic conditions are associated with a secondary reactive hyperaldosteronism by renin-angiotensin cascade activation http://en.wikipedia.org/wiki/Hypovolemia
Hypovolemia can be recognized by tachycardia, diminished blood pressure, and the absence of perfusion as assessed by skin signs (skin turning pale) and/or capillary refill on forehead, lips and nail beds. The patient may feel dizzy, faint, nauseated, or very thirsty.
Good thinking on the renal blood flow and connection to aldosterone! http://www.endotext.org/adrenal/adrenal23/adrenal23.htm
renin (and consequently aldosterone) production is stimulated by low tubular sodium or low renal perfusion;
So, I'm thinking maybe high, not low, aldosterone could be causing some of your issues. I don't know though. Will you share your levels when you get them? I promise to excitedly jump up and down like jimmylegs when she sees vitamin D levels.