title: Decrease of asymmetric dimethylarginine predicts acute mountain sickness.
abstract: BACKGROUND
  Each year, 40 million tourists worldwide are at risk of getting acute mountain sickness (AMS), because they travel to altitudes of over 2500 m. As asymmetric dimethylarginine (ADMA) is a nitric oxide synthase (NOS) inhibitor, it should increase pulmonary artery pressure (PAP) and raise the risk of acute mountain sickness and high-altitude pulmonary edema (HAPE). With this in mind, we investigated whether changes in ADMA levels (Δ-ADMA) at an altitude of 4000 m can predict an individual's susceptibility to AMS or HAPE.
  
  
  METHODS
  Twelve subjects spent two nights in a hypobaric chamber, the first night without exposure to altitude conditions and the second night at a simulated altitude of 4000 m. At identical time points during both nights (after 2, 5, and 11 hours), we determined ADMA serum levels, PAP by Doppler echocardiography and estimated hypoxia related symptoms by Lake Louise Score (LLS).
  
  
  RESULTS
  Contrary to our initial hypothesis, subjects with a marked increase in ADMA at 4000 m showed PAP levels below the critical threshold for HAPE and were not affected by AMS. By contrast, subjects with a decrease in ADMA suffered from AMS and had PAP levels above 40 mmHg. After 2 hours of hypoxia we found a significant relationship between Δ-PAP t(2) (Spearmans ρ = 0.30, p ≤ 0.05) respectively Δ-ADMA t(2) (ρ = -0.92, p ≤ 0.05) and LLS.
  
  
  CONCLUSIONS
  After 2 hours of hypoxia, the Δ-ADMA (positive or negative) can predict an LLS of >5 with a sensitivity of 80% and a specificity of 100% and can help assess the risk of an increase in PAP to more than 40 mmHg and thus the risk of HAPE (ϕ coefficient: 0.69; p ≤ 0.05).
authors: Departments of General and Thoracic Surgery, German Armed Forces Hospital of Ulm, Ulm, Germany. markus.tannheimer@arcor.de
authors: Markus
authors: M
authors: Tannheimer
authors: Kerstin
authors: K
authors: Hornung
authors: Matthias
authors: M
authors: Gasche
authors: Bernd
authors: B
authors: Kuehlmuss
authors: Matthias
authors: M
authors: Mueller
authors: Heiko
authors: H
authors: Welsch
authors: Klaus
authors: K
authors: Landgraf
authors: Christoph
authors: C
authors: Guger
authors: Roland
authors: R
authors: Schmidt
authors: Jürgen Michael
authors: JM
authors: Steinacker
mesh_terms: D000208:Acute Disease; D000328:Adult; D000532:Altitude Sickness / Q000150:complications / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood; D004198:Disease Susceptibility / Q000097:blood / Q000503:physiopathology; D015150:Echocardiography, Doppler / Q000379:methods; D004791:Enzyme Inhibitors / Q000097:blood; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D008297:Male; D009051:Mountaineering / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011669:Pulmonary Wedge Pressure; D012107:Research Design; D018570:Risk Assessment; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; C018524:N,N-dimethylarginine; D001120:Arginine; D019001:Nitric Oxide Synthase