Differential homeostatic reorganization during high-altitude trekking: multisystemic adaptations and organ-specific resilience.

INTRODUCTION: High-altitude exposure combined with physical activity triggers complex systemic adaptations. However, multidisciplinary longitudinal investigations into these multiorgan responses remain limited. This prospective observational study aimed to investigate the cardiovascular, metabolic, renal, and hepatic responses to a subacute high-altitude expedition. METHODS: 21 Caucasian participants (14 men and 7 women) participated during a Himalayan trek expedition up to 5050 m. Measurements included: cardiovascular parameters (HR, BP) evaluated at five points (baseline (T0), intermediate ascent (T0a), peak (T1), intermediate descent (T1a), post-trek (T2)); comprehensive biochemical parameters (renal, hepatic, and lipid markers) collected at four time points: baseline (T0), peak altitude (T1), post-trek (T2), and a several-month follow-up (T3); body weight at three points (T0, T1, T2) and dietary intake. RESULTS: Ascent induced significant increases in HR and BP, with DAP remaining elevated during descent. At peak altitude, the A/G ratio decreased while U/C and GFR increased, alongside reductions in creatinine and body weight. Despite a severe energy deficit (44-52% below predicted TDEE) and high lipid intake, total cholesterol, LDL, and HDL decreased significantly. Notably, markers of hepatic and muscular injury (AST, ALT, ALP, CK) remained stable throughout the expedition. CONCLUSION: Subacute high-altitude trekking imposes a selective physiological strain rather than uniform systemic stress. The body prioritizes vital hemodynamic and renal adaptations; at the same time, despite a negative energy balance, it exhibits organ-specific resilience, as demonstrated by hepatic and muscular stability. Finally, the complete recovery of markers at follow-up confirms these multisystemic shifts are highly adaptive and non-pathological.