Platelet count in temporary residents of high altitude.

Platelet count was estimated in 65 lowlanders temporarily staying at altitudes above 3,000 m. They were divided in subgroups according to the length of their continuous stay. For comparison, 51 highlanders who were born and reared at high altitude and 48 lowlanders who had never been to an altitude of more than 1,000 m were also studied. Gradually rising counts becoming highly significant (P < 0.001) as compared to the lowlanders after 31 days of stay and stabilizing close to the values in highlanders after 181 days were noted. The significance of these findings in the light of existing knowledge is discussed.