Posting of soldiers and officers from plains and low altitude areas to high altitude areas enhances the risk of thrombosis, a potentially life-threatening condition, where blood clots block the arteries and veins, researchers of a new study said.
The finding of the study, conducted by researchers from health services of the Indian Defence establishments, was published in the journal, The Lancet Regional Health - Southeast Asia recently.
During the study, the researchers screened 960 healthy males in the plains and followed up with 750 of them who ascended, to altitudes above 15,000 feet.
The participants were subjected to clinical examination, and tests for complete blood count, ability and time taken for the blood to coagulate along with, markers of inflammation and narrowing of large arteries even without any evidence of blockage, and were studied three times during ascent and descent.
During the trial, while 12 participants developed thrombosis of the veins, three developed arterial thrombosis, the researchers reported.
Compared to the control group (healthy individuals living in the plains), those who were posted in the high-altitude areas had decreased levels of natural anticoagulants in their blood.
The study also found that the ability to destroy clots among those who developed thrombosis also remained subdued due to low levels of tissue plasminogen activator (tPA) enzyme, which is found in the cell lining the blood vessels and helps to form other enzymes that break down clots in the vessels naturally.
Noting that all thrombotic events occurred above 15,000 feet among the healthy participants, the researchers said that a lack of oxygen at these heights could be an independent risk factor for thrombosis.
The lack of oxygen triggers inflammation and narrowing of the blood vessels even in the absence of blockage which may have resulted in increased incidences of coagulation in these people.
“This provides a platform to launch further studies to identify high-risk subjects for thrombosis and any intervention to prevent the same,” the researchers concluded.