Objective      To compare the effects of oxygen or oxygen combined with soyaisoflavones on the serum level of haemoglobin (HGB) in people living in high-altitudes plateau.       Methods      A total of 198 adults

living in the altitude of 3 500 to 5 300 m for more than 10 months

were enrolled in this study. According to the level of HGB before interventions

the cohort were divided into 3 groups (each group with 66 cases)

group A (≥210 g/L)

group B (190≤HGB＜210 g/L) and group C (150 ≤HGB190 g/L). Each group was then randomly divided into 2 subgroups (n=33) according to different intervention

group 1 was given low-flow oxygen therapy for 1.5 h

2-4 times per day

with a consecutive 90 d; and group 2 was given low-flow oxygen therapy combined with oral administration of 40 mg soyaisoflavones per day

with the treatment for 90 d. After 12 weeks

blood routine examination and follow-up survey were performed.       Results       ①After 12 weeks follow-up

the serum level of HGB was decreased in each subgroup except C1 (A1

A2

B1

B2 and C2 groups

compared with the levels before treatment

P0. 05); ② No significant difference was seen between C1 and C2 (P0.05). Oxygen and soyaisoflavones co-treatment significantly reduced the haemoglobin level than oxygen alone (P0.05); ③The level of haemoglobin was decreased more significantly in the A2 subgroup (P0.05)

followed by B2 subgroup (P0.05). Clinical symptoms were improved more obviously after intervention in the co-treatment than oxygen alone.       Conclusion      In high-altitude plateau areas

low-flow oxygen therapy combined with oral administration of soyaisoflavones is more effective in the prevention and treatment of high-altitude polycythemia. There may exist positive correlation between this improvement and hemoglobin level. The higher hemoglobin level

more effective is the combined treatment.