title: Hematological parameters in high altitude residents: Tibetan natives versus Han migrants.
abstract: OBJECTIVE
  Aim of our study was to compare hematological parameters in Tibetan natives with those in Han migrants living on the Tibet plateau in order to determine the potential effects of age, gender, and ethnicity on hematological response to hypoxia.
  
  
  METHODS
  Blood hemoglobin (Hb, g/dl), hematocrit (Hct, %), red blood cells (RBC,10(6)/mm3) were measured in 3 588 healthy Tibetan natives and 3 371 Han migrants ranging in age from 5 to 72 years, living at a mean altitudes of 2 664 m, 3 813 m, 4 525m and 5 226 m.
  
  
  RESULTS
  Hemoglobin (Hb) concentration analysis was made by multiple regression equations relating hemoglobin to altitude and age. For 2 093 Han males, Hb = 9.612+ 0.001440xaltitude+ 0.06148xage. For 1 948 Tibetan males, Hb =12.202+ 0.000462xaltitude+ 0.02893xage. For 1 278 Han females, Hb = 10.858+ 0.000939xaltitude+ 0.02632xage. For 1 640 Tibetan females, Hb = 11.402+ 0.000626xaltitude+ 0.00412xage. Each of the four equations was statistically significant (P < 0.001), and had variance (r2) of 0.86 or more, indicating that altitude and age accounted for at least 85% of the variation in hemoglobin levels. The coefficients for altitude and for age were higher (P < 0.05) in Han males than in Tibetan males and higher (P < 0.05) in Han females than in Tibetan females. The Tibetan postmenopausal females had higher Hb values than premenopausal females only presented at altitude above 4 000 m while this phenomenon was beginning at altitude of 2 664 m among Han females.
  
  
  CONCLUSIONS
  We conclude that gender and increasing age in Tibetans are associated with lower hemoglobin values than those in Han at high altitude, and we speculate that genetic factors seems to be important.
authors.forename: Tian-Yi
authors.initials: TY
authors.lastname: Wu
authors.forename: Feng-Yun
authors.initials: FY
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Hu
authors.forename: Chun-Yin
authors.initials: CY
authors.lastname: Wei
authors.forename: Zhi-Gang
authors.initials: ZG
authors.lastname: Wang
authors.lastname: Ouzhou-Loubu
authors.forename: Chao-Ying
authors.initials: CY
authors.lastname: Cu
authors.lastname: Bianba
authors.forename: Xue-Bin
authors.initials: XB
authors.lastname: Qi
authors.forename: Bing
authors.initials: B
authors.lastname: Su
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000531:Altitude; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D005006:Ethnicity; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D000860:Hypoxia / Q000208:ethnology*; D008297:Male; D008875:Middle Aged; D018609:Tibet; D014171:Transients and Migrants; D055815:Young Adult
chemical_list: D006454:Hemoglobins