D-Dimer Is Not Elevated in Asymptomatic High Altitude Climbers after Descent to 5340 m: The Mount Everest Deep Venous Thrombosis Study (Ev-DVT)

Zafren, Ken, Joane Feldman, Robert J. Becker, Sarah R. Williams, Eric A Weiss, and Tom Deloughery. D-dimer is not elevated in asymptomatic high altitude climbers after descent to 5340 meters: the Mount Everest deep venous thrombosis study (Ev-DVT). High Alt. Med. Biol. 12:223–227, 2011.—We performed this study to determine the prevalence of elevated D-dimer, a marker for deep venous thrombosis (DVT), in asymptomatic high altitude climbers. On-site personnel enrolled a convenience sample of climbers at Mt. Everest Base Camp (Nepal), elevation 5340 m (17,500 ft), during a single spring climbing season. Subjects were enrolled after descent to base camp from higher elevation. The subjects completed a questionnaire to evaluate their risk factors for DVT. We then performed a D-dimer test in asymptomatic individuals. If the D-dimer test was negative, DVT was considered ruled out. Ultrasound was available to perform lower-extremity compression ultrasounds to evaluate for DVT in case the D-dimer was positive. We enrolled 76 high altitude climbers. None had a positive D-dimer test. The absence of positive D-dimer tests suggests a low prevalence of DVT in asymptomatic high altitude climbers.