Creating an altitude-adjusted hematocrit reference standard for adults 18-40 years of age in China

This study was conducted to provide a scientific basis for development of a unified hematocrit reference standard for young adults (i.e., 18-40 yr of age) in China. Hematocrit values for healthy young adults (n = 34,383 men and 24,040 women) were collected in accordance with the Wintrobe method. The author used correlation and regression analyses to investigate the relationship between hematocrit values and altitude. Hematocrit values increased gradually with altitude, and the relationship was statistically significant (p < 0.01). It was determined that regression equations could be used to calculate hematocrit reference standards for healthy male and female adults in the aforementioned age group, provided that the mean altitude of a region was used in the analysis. The author offers examples that represent 3 regions of China characterized by different mean altitudes: (1) Qingzang District (4,000-m altitude), Central District (2,000-1,000 m), and Eastern District (< 500 m).