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Renin, aldosterone, electrolyte, and cortisol responses to hypoxic decompression
Summary
Hypoxic decompression to 4,760m altered hormone levels, decreasing plasma aldosterone and increasing plasma cortisol in men. These hormonal changes during acute mountain sickness require further investigation.
Area of Science:
- Physiology
- Altitude Medicine
- Endocrinology
Background:
- Acute mountain sickness (AMS) is a common condition at high altitudes.
- Hormonal responses to hypoxia are not fully understood.
- Previous studies have shown varied effects of altitude on the renin-angiotensin-aldosterone system and cortisol.
Purpose of the Study:
- To investigate the hormonal and electrolyte responses to simulated high altitude exposure.
- To examine changes in plasma renin activity, aldosterone, cortisol, and electrolytes during hypoxic decompression.
- To correlate hormonal changes with the development of acute mountain sickness.
Main Methods:
- Four healthy men were exposed to a simulated altitude of 4,760 m in a pressure chamber.
- Plasma samples were analyzed for renin activity, aldosterone, cortisol, sodium, and potassium.
- Urinary samples were analyzed for electrolytes and aldosterone.
- Subjects were monitored for symptoms of acute mountain sickness.
Main Results:
- Plasma sodium and potassium concentrations remained unchanged.
- Plasma renin activity showed a non-significant trend towards decrease.
- Plasma aldosterone concentration was depressed, while plasma cortisol was elevated and lost its diurnal variation.
- Urinary sodium excretion was unchanged, but urinary potassium and aldosterone excretion decreased.
- Three out of four subjects developed significant acute mountain sickness.
Conclusions:
- Hypoxic decompression to 4,760 m leads to decreased plasma and urinary aldosterone and increased plasma cortisol.
- The observed hormonal changes, particularly the decrease in aldosterone without a change in renin activity, are of uncertain origin.
- The elevated plasma cortisol, despite the absence of decreased adrenocorticotropin secretion, warrants further study.
- While hormonal changes occurred, a direct causal link to acute mountain sickness could not be established, though cortisol increase was greatest in the most ill subjects.