Glomerular filtration rate estimates decrease during high altitude expedition but increase with Lake Louise acute...

Area of Science:

• Altitude physiology
• Renal function
• High-altitude medicine

Background:

• Acute mountain sickness (AMS) involves microvascular changes and edema.
• Limited data exists on glomerular filtration rate (GFR) changes above 5000m.
• Understanding renal function at extreme altitudes is crucial for mountaineer safety.

Purpose of the Study:

• To investigate changes in estimated GFR (eGFR) in healthy individuals ascending above 5000m.
• To determine the relationship between eGFR, AMS severity, and physiological markers.
• To assess the impact of different acclimatization protocols on renal function at high altitude.

Main Methods:

• 34 healthy mountaineers participated in a high-altitude expedition (Muztagh Ata, 7549m).
• eGFR was measured using cystatin C and creatinine at various altitudes (450m to 6865m).
• Lake Louise AMS scores and other physiological parameters were recorded.

Main Results:

• eGFR significantly decreased with increasing altitude, showing a linear decline of approximately 3.1 mL/min/1.73m² per 1000m ascent.
• Cystatin C-based eGFR showed a significant decrease between base camp (4497m) and Camp 3 (6865m).
• Higher AMS scores were significantly associated with higher eGFR, and eGFR correlated with hematocrit.

Conclusions:

• Renal function, specifically eGFR, declines during ascent to high altitudes.
• Cystatin C-based eGFR decreases with altitude but increases with AMS severity.
• Individuals with eGFR below 40 mL/min/1.73m² should be cautious when traveling above 4500m.