Do mountain dwellers suffer from polyuria (excessive urine production)?

Mountain Dwellers and Polyuria

Yes, mountain dwellers do experience polyuria (excessive urine production) as part of the physiological adaptation to high altitude exposure. 1

Mechanism of Altitude-Induced Polyuria

• High altitude exposure triggers physiological acclimatization processes within the cardiocirculatory and pulmonary systems due to decreased barometric pressure and lower partial pressure of oxygen in inspired air 1
• This hypobaric hypoxia leads to a rapid increase in respiratory rate and tidal volume, causing respiratory alkalosis 1
• The respiratory alkalosis directly contributes to what is known as "hypoxic diuresis" or "altitude diuresis" 1, 2
• The renal effects are mediated by atrial natriuretic peptide release and slight suppression of arginine-vasopressin (AVP) secretion 2

Clinical Manifestations

• Increased urine output occurs during the initial days at high altitude 2
• This diuresis helps offset the cardiac volume overload resulting from hypoxic stimulation of arterial chemoreceptors 2
• The polyuria is typically accompanied by natriuresis (increased sodium excretion in urine) 2
• The diuretic effect is most pronounced during the initial acclimatization period 3

Factors Affecting Altitude Diuresis

• Acclimatization status: Both acclimatized and non-acclimatized individuals experience altitude diuresis, but the response may differ in timing and magnitude 2
• Altitude level: More pronounced effects are typically seen at higher elevations (>2,500 meters above sea level) 1
• Individual susceptibility: Some individuals are more prone to fluid shifts and may develop acute mountain sickness (AMS) 3
• Hydration status: Proper hydration is important as dehydration can worsen symptoms of altitude sickness 3

Clinical Significance

• The increased urine output serves as a compensatory mechanism to help the body adapt to high altitude conditions 2
• This diuresis reduces cardiac volume overload that results from hypoxic stimulation 2
• In patients with heart failure, this physiological response may be impaired, potentially increasing the risk of cardiac decompensation at high altitude 1
• Patients taking medications such as ACE inhibitors or angiotensin receptor blockers may have altered responses to altitude as these drugs can reduce renal erythropoietin production 1

Management Considerations

• Diuretic therapy should be tailored individually when traveling to high altitude locations to account for the natural hypoxic diuresis 1
• Patients with heart failure should be assessed for safety of high altitude exposure based on their functional capacity at sea level 1
• Proper hydration should be maintained despite increased urine output to prevent dehydration 3
• Monitoring for signs of acute mountain sickness is important, as those developing AMS may show altered fluid balance with reduced urine output rather than the expected diuresis 3

Special Populations

• Patients with cardiovascular conditions require special consideration when traveling to high altitudes 1
• Travel to intermediate altitudes (~2,000 m) is generally safe for patients with heart failure who have good exercise tolerance at sea level 1
• Elderly individuals may be more susceptible to the physiological changes induced by altitude 1

In conclusion, polyuria is a normal physiological response to high altitude exposure in mountain dwellers, serving as an adaptive mechanism to help maintain fluid balance and cardiovascular function in the face of hypobaric hypoxia.