REPRODUCIBILITY OF FIBRINOLYTIC RESPONSE TO VENOUS OCCLUSION IN HEALTHY-SUBJECTS

Fibrinolytic response to venous occlusion is used to assess the effici ency of the fibrinolytic system. Reproducibility of fibrinolytic varia bles after 20 min upper arm venous occlusion was investigated in 40 ap parently healthy subjects tested twice in a period of 11-23 (mean 15) days. Resting and post-venous occlusion euglobulin clot lysis time, ti ssue-type plasminogen activator (t-PA) activity, t-PA antigen, plasmin ogen activator inhibitor (PAI) activity and plasminogen activator inhi bitor type 1 (PAI-1) antigen determined on the two occasions did not d iffer significantly. Positive correlation coefficients fur variables b efore (r=0.43-0.74, all p<0.01) and after venous occlusion (r=0.07-0.6 6) indicated low to moderate associations between repeated measurement s. Differences between repeated measurements relative to the initial m easurement were greater after venous occlusion than before venous occl usion and were for euglobulin activity 41 (0-826)%, t-PA activity 27 ( 2-398)%, and for t-PA antigen 27 (0-179)% (medians and ranges). Poor r esponses were defined by the lowest (eug]obulin activity, t-PA activit y and t-PA antigen) or the highest (PAI activity) fifth percentile of the distribution. Almost no agreement between poor responses was obser ved: poor responses at the first occasion were not determined in the s ame subjects when re-examined after two weeks. It was concluded that d ue to relatively low reproducibility of the variables measured after v enous occlusion the test needs improvement in order to be potentially clinically useful.