The overlooked significance of plasma volume for successful adaptation to high altitude in Sherpa and Andean natives

Mike Stembridge, Alexandra M. Williams, Christopher Gasho, Tony G. Dawkins, Aimee Drane, Francisco C. Villafuerte, Benjamin D. Levine, Rob Shave, Philip N. Ainslie

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


In contrast to Andean natives, high-altitude Tibetans present with a lower hemoglobin concentration that correlates with reproductive success and exercise capacity. Decades of physiological and genomic research have assumed that the lower hemoglobin concentration in Himalayan natives results from a blunted eryth-ropoietic response to hypoxia (i.e., no increase in total hemoglobin mass). In contrast, herein we test the hypothesis that the lower hemoglobin concentration is the result of greater plasma volume, rather than an absence of increased hemoglobin production. We assessed hemoglobin mass, plasma volume and blood volume in lowlanders at sea level, lowlanders acclimatized to high altitude, Himalayan Sherpa, and Andean Quechua, and explored the functional relevance of volumetric hematological measures to exercise capacity. Hemoglobin mass was highest in Andeans, but also was elevated in Sherpa compared with lowlanders. Sherpa demonstrated a larger plasma volume than Andeans, resulting in a comparable total blood volume at a lower hemoglobin concentration. Hemoglobin mass was positively related to exercise capacity in lowlanders at sea level and in Sherpa at high altitude, but not in Andean natives. Collectively, our findings demonstrate a unique adaptation in Sherpa that reorientates attention away from hemoglobin concentration and toward a paradigm where hemoglobin mass and plasma volume may represent phenotypes with adaptive significance at high altitude.

Original languageEnglish (US)
Pages (from-to)16177-16179
Number of pages3
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number33
StatePublished - Aug 13 2019


  • Altitude
  • Andeans
  • Hemoglobin
  • Hypoxia
  • Tibetans

ASJC Scopus subject areas

  • General


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