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Coagulation laboratory tests

Plasminogen activator antigen-1

Reviewer: Jeremy Parsons, M.D. (see Reviewers page)
Revised: 10 February 2013, last major update November 2012
Copyright: (c) 2002-2013, PathologyOutlines.com, Inc.


● Uncommon test; perform if strong evidence of familial bleeding disorder, but normal results for von Willebrand disease or possibly if unexplained premature myocardial infarction
● May predict severe hepatic veno-occlusive disease after allogeneic bone marrow transplantation (Br J Haematol 2002;118:1087)
● Not a known risk factor for hypercoagulability (Arch Pathol Lab Med 2002;126:1401), although high levels are associated with arterial thrombosis; low levels are associated with rare familial bleeding disorder
● Has circadian rhythm with highest values in morning; in one study, mean level was 23 ng/mL at 9 am vs. 10 ng/mL at 4 pm; also is acute phase reactant, so donít measure immediately following thrombosis; also elevated during pregnancy


Collection: collect blood from steadily flowing venipuncture, discard first 3-5 mL (if this is the only test) and avoid platelet contamination of plasma (platelets contain PAI1) by separating plasma from cells or storing on ice
● Reject specimen if antifibrinolytic agent is present in specimen
Reference range: 4-40 ng/mL for antigen assay, 0-12 units/mL for functional assay
Functional assay: add patient plasma to known amount of urokinase / tPA, which binds to patient PAI1; residual urokinase is detected by adding plasminogen, which converts it to plasmin, which cleaves a chromogenic substrate; amount of released color is inversely proportional to patient PAI1 (note: inhibitors of antiplasmin and plasmin are present to prevent their interference)
ELISA (antigen) assay: also available

End of Coagulation > Coagulation laboratory tests > Plasminogen activator antigen-1

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