Coagulation laboratory tests
Antiplasmin assay

Topic Completed: 1 June 2012

Revised: 7 January 2019, last major update June 2012

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

PubMed Search: Antiplasmin assay [title]

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Cite this page: Parsons J. Antiplasmin assay. website. Accessed June 1st, 2020.
Definition / general
  • Also called anti - alpha2 - antiplasmin, plasmin inhibitor
  • An uncommon assay usually sent to reference laboratories

  • Indications:
    • Familial bleeding disorder, after ruling out more common bleeding disorders such as von Willebrand disease
    • True alpha2 - antiplasmin deficiency is a rare condition (< 20 cases)
    • Most cases are caused by inhibitors (antibodies)

  • Specimen:
    • Plasma in citrate tube, without epsilon - aminocaproic acid, aprotinin, heparin or other fibrinolysis inhibitors

  • Reference range:
    • Approximately 48 - 80 mg / dL, lower during first 5 days of life

  • Functional assays:
    • Add specific amount of excess plasmin to patient’s plasma, measure plasmin that is unbound to antiplasmin in patient’s serum by detecting color change spectrophotometrically
    • Amount of unbound plasmin detected is inversely proportional to patient’s antiplasmin level

  • Antigenic (immunologic) assay:
    • Patient’s plasma in placed in the cylindrical well of an agarose gel containing antiplasmin antibody, which defuses into the well and forms an antigen - antibody complex and precipitin ring
    • The size of the ring is proportional to the patient’s antiplasmin

  • Acquired causes of decreased antiplasmin:
    • Liver disease, thrombolytic therapy, DIC

Additional references
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