Study reveals role of kidneys in high altitude acclimatization

A study from a Mount Royal University physiologist and his team demonstrates the key role of the kidneys in acclimatization to high altitude, and illustrates another way that Sherpas are better adapted to high altitude ascent.

Results from the study were recently published in in the prestigious international science journal Proceedings of the National Academy of Sciences. 

The paper, "Comparing integrative ventilatory and renal acid-base acclimatization in lowlanders and Tibetan highlanders during ascent to 4,300 m", describes findings from an international high altitude research expedition to the Nepal Himalaya, funded by NSF (USA) and NSERC (Canada), where the team led by Dr. Trevor Day, PhD, studied the blood acid-base acclimatization responses to incremental ascent in lowlanders and Tibetan highlanders (Sherpa). 

The team found that Sherpa participants had more rapid and larger magnitude blood acid-base acclimatization than lowlanders with incremental ascent to 4,300 metres. This study highlights the key role of the kidneys in acclimatization to high altitude, and illustrates another way that Sherpa are better adapted to high altitude ascent. 

With so many people now living and traveling to high altitudes, understanding integrated acclimatization and adaptation to high altitude in human populations is of increasing importance, particularly comparing lowlander to highlander populations."

Dr. Trevor Day, PhD, Mount Royal University

 High altitude exposure imposes a blood oxygenation and acid–base challenge, compensated by respiratory and renal acclimatization. The team assessed respiratory and renal acclimatization between unacclimatized age- and sex-matched groups of lowlanders and Tibetan highlanders (Sherpa) during incremental ascent to 4,300 metres in the Nepal Himalaya. Sherpa had a larger magnitude and more rapid time-course of respiratory and renal acclimatization, resulting in fully compensated blood pH at 4,300 metres, whereas lowlanders were still alkalemic.

"This study provides insight into the interplay of ancestry and physiological mechanisms contributing to acclimatization to high altitude, which may indicate selective pressure on ancestral Tibetan highlander populations related to renal function with acclimatization."

Insights from the research benefit physiology as a whole, and add new understanding about how different populations acclimatize to high altitude ascent. 

The study's co-first authors were MRU undergraduate trainees Nicole Johnson and Jessica Dickenson, with contributions from two other MRU undergraduate trainees, Benjamin Mackenzie and Rodion Isakovich, and fellow MRU faculty member Dr. Nick Strzalkowski. With support from medical resident Dr. Anne Kalker and post-doctoral fellow Dr. Janne Bouten, both from Europe, rounded out by collaborators in Nepal and organizational help from collaborators in the U.S. Drs. Taylor Harmon, Abigail Bigham, Tom Brutsaert and Sweden, Dr. Pontus Holmstrom, this project represents a huge international effort, resulting from the team's high altitude research expedition to Nepal in 2023.