Altitude Influence on the Rare Occurence of Thrombosis on the Andes Plateaus

Abstract

The very low frequency of arterial thrombosis and atherosclerosis in the subjects living at high altitude in Bolivia led us to study on 200 subjects: the diet, blood lipids, coagulation factors and platelet functions in their own plasma or after filtration on Sepharose 2B followed by resuspension in their own plasma or in human fibrinogen solution plus non purified γ globulins.Compared to European controls studied at sea level, Bolivian highlanders have – a normal calorie intake, but the fat ingested is essentially vegetal – a low cholesterol level (173 mg/100 ml±49) – a high triglyceride level (142 mg/100 ml±48) – clotting factors within the normal range – a poor fibrinolytic response to anoxia induced by venous stasis (152 mn/202 mn) — an increased platelet count (315,000/mm3±70) – a platelet liypo-aggregaljility witli ADP 0,8 μM (desaggregation occurs in more than 80 per cent of the subjects) with epinephrin (desaggregation occurs between 2,5 and 0,5 μM) but not with collagen. This hypoaggregability seems to be of plasma origin since gel filtered platelets aggregate better when resuspended in fibrinogen and γ globulins than in their own plasma.The same difference is found if native highlanders are compared to Indian lowlanders who migrated to high altitude, especially in the young people (15/25 years). This difference can be related to the time spent at high altitude.It is concluded that the particular behaviour of platelet and fibrinolysis of the native highlanders can be produced by a life-time adaptative process in the non native people.