Analysis on Serological Parameters Related to Erythrocyte Metabolism of People in Areas at Different High-altitude in Tibet

  Objective  To explore the characteristics of serological parameters related to erythrocyte metabolism in Tibetans living at different altitudes in Tibet, and to establish the reference intervals of each parameter.

  Methods  The cluster-sampling method was used to randomly select residents from Ngari (altitude Ⅰ, 4298-4352 m), Lhasa and Xigaze (altitudeⅡ, 3670-3835 m), and Nyingchi (altitude Ⅲ, about 2900 m) in Tibet from September 2016 to August 2018. Blood samples were collected for the determination of the whole blood-cell count, serum iron (SI), unsaturated ironbinding capacity (UIBC), transferrin (TRF), ferritin (FER), folic acid (FA), and vitamin B₁₂(Vit B₁₂). Transferrin saturation (TSAT) was calculated. Multiple linear regression and variance component analysis were used to compare the differences in gender, age, and altitude for various laboratory parameters among Tibetan population. The reference intervals of the laboratory parameters were established by the transformed parameter method.

  Results  A total of 1128 Tibetans were included in this study, of which 937 subjects were used to establish the reference intervals. The levels of SI, TSAT and FER in males were significantly higher than those in females (all P < 0.001). TRF, FA and UIBC in males were significantly lower than those in females (all P < 0.001). TRF and UIBC decreased with age; FER increased with age; the highest Vit B₁₂ was in the 30-39 age group; SI, TSAT, FER and Vit B₁₂ increased with altitude (all P < 0.001); the highest TRF and UIBC were at the altitude Ⅱ and the lowest at the altitude Ⅲ. The reference intervals of each index is shown as follows: 4.5-35.6 μmol/L in females and 10.6-41.1 μmol/L in males for SI; 19.9-79.5 μmol/L in females and 16.4-63.9 μmol/L in males for UIBC; 1.90-3.64 g/L for TRF; 5.3%-58.2% in females and 16.4%-68.8% in males for TSAT; 4.81-953.15 μg/L in females at the altitude Ⅰ and Ⅱ, 4.85-459.53 μg/L in females at the altitude Ⅲ, 50.55-1677.28 μg/L in males at altitude Ⅰ and Ⅱ, and 48.68-1239.30 μg/L in males at altitude Ⅲ for FER; 1.96-9.76 μg/L for FA; 176.3-1162.3 ng/L for Vit B₁₂.

  Conclusions  There are gender/age/altitude differences in serological parameters related to erythrocyte metabolism among residents in areas at the high altitude. The distribution is also different from that in plain areas. Therefore, it is necessary to establish specific reference intervals for the population in Tibet.