title: High-altitude gastrointestinal bleeding: an observation in Qinghai-Tibetan railroad construction workers on Mountain Tanggula.
abstract: OBJECTIVE
  To investigate the gastrointestinal bleeding (GIB) in people from lowland to high altitude and in workers on Mountain Tanggula and its causes as well as treatment and prophylaxis.
  
  
  METHODS
  From 2001 to October 2003, we studied GIB in 13502 workers constructing the railroad on Mountain Tanggula which is 4905 m above the sea level. The incidence of GIB in workers at different altitudes was recorded. Endoscopy was performed when the workers evacuated to Golmud (2808 m) and Xining (2261 m). The available data on altitude GIB were analyzed.
  
  
  RESULTS
  The overall incidence of GIB was 0.49% in 13502 workers. The incidence increased with increasing altitude. The onset of symptoms in most patients was within three weeks after arrival at high altitude. Bleeding manifested as hematemesis, melaena or hematochezia, and might be occult. Endoscopic examination showed that the causes of altitude GIB included hemorrhage gastritis, gastric ulcer, duodenal ulcer, and gastric erosion. Experimental studies suggested that acute gastric mucosal lesion (AGML) could be induced by hypoxic and cold stress, which might be the pathogenesis of altitude GIB. Those who consumed large amount of alcohol, aspirin or dexamethasone were at a higher risk of developing GIB. Persons who previously suffered from peptic ulcer or high-altitude polycythemia were also at risk of developing GIB. Early diagnosis, evacuation, and treatment led to early recovery.
  
  
  CONCLUSIONS
  GIB is a potentially life threatening disease, if it is not treated promptly and effectively. Early diagnosis, treatment and evacuation lead to an early recovery. Death due to altitude GIB can be avoided if early symptoms and signs are recognized.
authors.affiliation: Physiological Research Group of Ministry of Railway, High Altitude Medical Research Institute, Xining 810012, Qinghai Province, China. wutianyiqh@hotmail.com
authors.forename: Tian-Yi
authors.initials: TY
authors.lastname: Wu
authors.forename: Shou-Quan
authors.initials: SQ
authors.lastname: Ding
authors.forename: Jin-Liang
authors.initials: JL
authors.lastname: Liu
authors.forename: Jian-Hou
authors.initials: JH
authors.lastname: Jia
authors.forename: Rui-Chen
authors.initials: RC
authors.lastname: Dai
authors.forename: Dong-Chun
authors.initials: DC
authors.lastname: Zhu
authors.forename: Bao-Zhu
authors.initials: BZ
authors.lastname: Liang
authors.forename: De-Tang
authors.initials: DT
authors.lastname: Qi
authors.forename: Yong-Fu
authors.initials: YF
authors.lastname: Sun
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology*; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology*; D011890:Railroads; D012307:Risk Factors