[Travelling to high altitudes: do not increase fluid intake]

Area of Science:

• Physiology
• Altitude Medicine
• Environmental Health

Context:

• High altitude exposure triggers physiological changes impacting fluid and electrolyte balance.
• Altitude sickness presents distinct fluid and sodium regulation patterns compared to acclimatized individuals.

Purpose:

• To investigate the fluid and sodium balance alterations in individuals experiencing altitude sickness.
• To determine the physiological mechanisms behind fluid retention during altitude sickness.
• To evaluate the efficacy of increased fluid intake for altitude illness prevention.

Summary:

• Individuals at high altitude initially exhibit negative water and sodium balance.
• Altitude sickness is associated with impaired diuresis and natriuresis, leading to positive fluid balance.
• Hormonal factors including renin-angiotensin-aldosterone system (RAAS) activation, increased antidiuretic hormone (ADH) secretion, and heightened sympathetic activity contribute to fluid retention.

Impact:

• Findings challenge the common recommendation for increased fluid intake to prevent altitude illness.
• Results suggest that increased fluid intake might be detrimental in cases of altitude sickness.
• Provides evidence-based insights for managing hydration strategies in high-altitude environments.