Summary
In the present study 57 consecutive patients with a first episode of venographically
proven deep vein thrombosis were investigated to evaluate the release of tissue-type
plasminogen activator (t-PA) and of urokinase-type plasminogen activator (u-PA) in
response to DDAVP stimulation as well as the resting plasminogen activator inhibitor
(PAI) concentration, comparing this to the results obtained in 66 similar patients
with a clinical suspicion of thrombosis but with a normal venogram. All assays were
performed without knowledge of the patient's status.
Four patients in the deep vein thrombosis-group (7%) had an absent u-PA antigen response
upon DDAVP infusion, while a normal response was observed in all control subjects.
Patients and controls showed similar increases in t-PA antigen level upon DDAVP. High
resting PAI antigen levels were encountered in 5 patients in the deep vein thrombosis-group
(9%) and in 6 subjects in the control group (9%).
The results from this controlled study indicate that a defective release of u-PA may
occur in patients with deep vein thrombosis and may have pathogenetic significance.
Furthermore it is concluded that elevation of PAI levels cannot be considered as a
specific risk factor for venous thrombosis.