Reference Range
Plasminogen activator inhibitor-1 (PAI-1) testing is indicated for unexplained mild-to-moderate delayed bleeding disorders, typically associated with trauma or surgery. [1]
Normal findings [2] :
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Antigen assay: 2-46 ng/mL
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Activity: < 31.1 IU/mL
Interpretation
Increased PAI-1 activity is observed in acute-phase reactions associated with the following: [3]
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Inflammation
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Cancer
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Postoperative period
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Diabetes
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Atherosclerosis and atherothrombosis
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Pregnancy
Two types of inherited PAI-1 deficiency exist, as follows: [1]
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Type I: Decreased functional and immunological PAI-1 levels
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Type II: Decreased functional activity despite normal protein concentration
Collection and Panels
Specimen: Citrated plasma
Collection: Blue-top tube with 3.2% sodium citrate
Centrifugation: 2000-2500 g for 15 minutes or similar method to produce platelet-poor plasma
Storage: Up to 2 hours at 2-8°C or the plasma sample should be frozen; specimen is stable for one month at -20°C or 6-9 months at -80°C
A high concentration of bilirubin might affect the PAI-1 measurement. Lipemic or hemolyzed samples should not be used.
Antifibrinolytic drugs (aminocaproic acid, tranexamic acid) could interfere with assay results and should not be used.
Background
Description
Plasminogen activator inhibitor-1 (PAI-1) is a glycoprotein (molecular weight, 47 kDa) that is synthesized in endothelial cells, hepatocytes, and adipocytes. It can also be released from activated platelets. PAI-1 circulates in the blood in both its active form (half-life of 30 minutes) and its latent form (half-life of 2 hours). PAI-1 is the main regulator of fibrinolytic system activation; it inhibits tissue-type plasminogen activators (tPA) and urokinase-type plasminogen activators (uPA). [1, 3]
Indications/Applications
PAI-1 testing is indicated for unexplained mild-to-moderate delayed bleeding disorders, typically associated with trauma or surgery. [1]
It is also indicated for idiopathic arterial or venous thromboembolism if other causes of thrombophilia are excluded. [4]
Considerations
The PAI-1 level has a diurnal variation, peaking in the early morning. [3] Repeated measurements of PAI-1 level or antigen or other fibrinolytic markers might be useful in confirming a persistently abnormal PAI-1 level as a cause of bleeding or thrombosis. [1, 3]