Summary
Two hundred and three patients with venous thrombophilia were investigated in order
to find out whether an elevated plasma concentration of plasminogen activator inhibitor
(PAI) could be a cause of their tendency to thrombosis. The patients were studied
in an asymptomatic period about 3 months after their last thromboembolic episode.
PAI activity was found to be elevated in 19 patients (9%), and a corresponding elevation
of PAI-1 antigen was observed.
In 16 out of the 19 patients with elevated PAI activity, followup could be performed
after an additional asymptomatic period of about 1 year: in eight patients the elevation
of PAI was transient and in eight it was persistent. Out of the eight patients with
a persistent elevation of PAI, seven had a positive family history of thrombosis.
Investigation of these families excluded a hereditary elevation of PAI activity in
two families. In only two other families was elevated PAI activity also found among
family members. The occurrence of elevated PAI activity, however, did not coincide
with the occurrence of thrombosis in these individuals: except for the probands, all
investigated family members who had a history of thrombosis had a normal PAI activity.
We therefore conclude that, at least in our material, familial thrombophilia can not
be attributed to an inherited, persistent elevation of the blood level of PAI.
Keywords
Plasminogen activator inhibitor - Venous thrombosis - Thrombophilia
