| Summary: | Abstract Background Many studies have indicated specific low-hemoglobin (Hb) adaptation to high altitude in the Tibetan population, but studies focusing on physiological variations within this population are limited. This study aimed to investigate the relationships between SpO2 and related factors, including individual variations and sex differences, to assess the generality of high-altitude adaptation in the Tibetan population of Tsarang. Methods The participants were 31 male and 41 female community-dwelling people aged ≥18 years living in Tsarang, in the Mustang district of Nepal. Height, weight, SpO2, Hb concentration, finger temperature, heart rate, and blood pressure were measured. Lifestyle information was obtained by interview. Results Men had significantly higher systolic blood pressure (p = 0.002) and Hb (p < 0.001) than women. There was no significant correlation between SpO2 and other parameters in men. In women, SpO2 was negatively correlated with heart rate (p = 0.036), Hb (p = 0.004), and finger temperature (p = 0.037). In multiple regression analysis, a higher SpO2 was marginally correlated with lower age (β = −0.109, p = 0.086) and higher Hb (β = 0.547, p = 0.053) in men. In women, higher SpO2 was significantly correlated with lower heart rate (β = −0.045, p = 0.036) and Hb (β = −0.341, p = 0.018). Mean hemoglobin (95% confidence interval) was 13.6 g/dl (13.1–14.0 g/dl), which is lower than that found previously in Andeans and almost equal to that in Japanese lowlanders measured using the same device. In some participants of both sexes, hemoglobin was >17.0 g/dl. Conclusion Higher SpO2 was marginally correlated with younger age and higher Hb in men and with lower heart rate and lower Hb in women. Hemoglobin concentration was similar to that found previously in lowlanders, but higher in some individuals. These results indicate individual variation and sex differences in the hemodynamics of high-altitude adaptation in Tibetan highlanders of Tsarang, as well as low-Hb adaptation to high altitude equal to that of other Tibetans.
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