Coagulation laboratory tests
tPA assay

Topic Completed: 1 November 2012

Revised: 7 January 2019, last major update November 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: tPA assay [title]

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Definition / general | Laboratory
Cite this page: Parsons J. tPA assay. website. Accessed May 24th, 2020.
Definition / general
  • tPA activity / antigen and PAI-1 activity / antigen are used to evaluate fibrinolysis; often PAI-1 activity and tPA antigen are ordered together
  • PAI-1 rapidly forms a complex with free tPA in the specimen
  • Not recommended for routine clinical laboratories due to complexity and special handling requirements
  • Can also measure tPA plasma concentration by ELISA or other immunologic assays
  • Resting level is usually low, not clinically significant
  • Post-stimulation level (such as after venous occlusion for 10 minutes) may be more useful
  • Higher levels in patients with acute paraquat intoxication (J Korean Med Sci 2011;26:474)
  • Must first inhibit interaction of tPA with PAI1 (its functional inhibitor) by acidifying plasma
  • Determine activity by measuring plasmin activity from conversion of plasminogen
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