Acclimatized Lowlanders Exhibit a Hypocoagulable Profile after a Passive Ascent at High Altitude

Area of Science:

• Altitude Medicine
• Physiology
• Hematology

Background:

• Previous research on high-altitude (HA) exposure and coagulation has yielded conflicting results.
• Understanding coagulation changes in lowlanders at HA is crucial for managing altitude-related health risks.

Purpose of the Study:

• To investigate alterations in coagulation parameters in lowlanders after a 14-day exposure to high altitude.
• To compare dynamic coagulation assays with conventional tests to assess HA-induced hemostatic changes.

Main Methods:

• Ten lowlanders underwent coagulation testing at low altitude (LA) and after 14 days at HA (up to 5,100 m).
• Assays included whole-blood rotational thromboelastometry (ROTEM), thrombin generation assay (TGA), and conventional coagulation tests.

Main Results:

• Conventional tests showed changes in coagulation factors within normal ranges.
• ROTEM revealed delayed clot initiation at HA without changes in clot firmness.
• TGA indicated a prolonged time to peak thrombin, decreased endogenous thrombin potential, and a lower thrombin peak at HA.

Conclusions:

• Lowlanders acclimatized to HA for 14 days do not develop hypercoagulability.
• Dynamic coagulation assays (ROTEM, TGA) demonstrate a hypocoagulable pattern at high altitude.