While it is well known that excesses of cortisol and aldosterone occur independently, it is important to realize that cortisol and aldosterone deficiencies may be independent, that is a patient may have only aldosterone deficiency, only cortisol deficiency or both deficiencies.
I recently found that many patients that have come to see me with the symptom of fatigue and often symptoms of salt-craving, “cognitive fuzziness”, dizziness or light-headedness on standing, or palpitations have low blood levels of aldosterone. The connection between low aldosterone levels and fatigue is as follows: With low aldosterone, the kidney loses salt, leading to low blood volume.
This coupled with the idea that the leg veins don’t constrict properly, leads to low blood volume going to the brain and the symptom of fatigue and other symptoms. These patients often have a drop in their blood pressure and an increase in their pulse when standing.
They may also have decreased blood flow to the brain when measured by SPECT scan. Aldosterone deficiency may be made worse if patients restrict their salt intake.
My soon-to-be published research has shown a few patterns of abnormalities in the renin-aldosterone axis. A little more than half of the patients with fatigue had low blood levels of both renin and aldosterone.
This is called hyporeninemic hypoaldosteronism and is probably due to dysfunction of what is called the autonomic nervous system, which sends messages from the brain to the kidneys.
Other aspects of the autonomic nervous system has been found to be deficient in chronic fatigue syndrome. About a third of the patients were found to have low aldosterone and high renin.
This indicates a deficiency in the aldosterone production in the adrenals themselves with a compensatory rise in the renin coming from the kidney. The aldosterone defect can either be isolated or part of Addison’s disease (often early Addison’s disease), in which both cortisol and aldosterone production are diminished.
The remaining patients had both high renin and high aldosterone.