Plasminogen Act Inhibitor-1,Ag

TEST: 146790
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CPT: 85415
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Synonyms

  • PAI
  • PAI-1
  • PAI1
  • Plasminogen Activator Inhibitor-1, Antigen

Special Instructions

If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions.

Expected Turnaround Time

4 - 7 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Specimen Requirements

Specimen

Plasma, frozen

Volume

1.0 mL

Minimum Volume

0.5 mL (Note: This volume does not allow for repeat testing.)

Container

Blue-top (sodium citrate) tube

Collection

Citrated plasma samples should be collected by double centrifugation. Platelet-poor plasma is needed. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp No. 49482). Freeze immediately and maintain frozen until tested.

Print and use the Specimen Collection Bulletin as a tube-filling guide.

Storage Instructions

Freeze

Causes for Rejection

Non-citrate plasma received; sample received unfrozen

Test Details

Use

Plasminogen activator inhibitor-1 (PAI-1) is a member of a family of proteins that inhibit plasminogen activators. 7,8 PAI-1 is a single-chain glycoprotein with a molecular weight of 47 kilodaltons. During fibrinolysis, tissue plasminogen activator (tPA) converts the inactive protein plasminogen into plasmin. Plasmin, in turn, plays a critical role in fibrinolysis by degrading fibrin and also provides localized protease activity in a number of physiological functions, including ovulation, cell migration, and epithelial cell differentiation. PAI-1 is the primary inhibitor of tPA and other plasminogen activators in the blood. PAI-1 limits the production of plasmin and serves to keep fibrinolysis in check. Uncontrolled plasmin production can result in excessive degradation of fibrin and an increased risk of bleeding. PAI-1 levels are, in part, controlled on a genetic basis.7 Certain polymorphisms in the PAI-1 gene are associated with increased blood concentrations. Increased PAI-1 levels have been shown to be associated with a number of atherosclerotic risk factors.7,8 Insulin and proinsulin correlate with PAI-1 levels. Patients with insulin resistance syndrome and diabetes mellitus tend to have increased PAI-1 levels. Weight loss and treatment aimed at lowering triglyceride and/or cholesterol levels have been shown to also lower PAI-1 levels. PAI-1 has been shown to act as a prothrombotic factor in both arterial and venous thromboembolic disorders.7,8 Increased levels of PAI-1 are associated with an increased incidence of acute coronary syndrome. PAI-1 levels are also increased in patients with chronic and acute coronary artery disease (CAD) and in patients who suffer restenosis after coronary angioplasty. It has also been shown that increased PAI-1 levels may reduce the effectiveness of antithrombolytic therapy.7,9 In fact, certain fibrinolytic agents, such as TNK-t-PA, are PAI-1-resistant and may be more effective in patients with increased PAI-1 levels. The method used for measuring PAI-1 activity in this test is an immunoassay that is specific for proteins that bind to tissue plasminogen activator (tPA) immobilized on a microtiter plate. The bound protein in then quantified using a monoclonal antibody that is specific for PAI-1.

Limitations

Samples containing platelets prior to freezing will give erroneously high results due to the release of latent PAI-1 from platelet granules. PAI-1 is an acute phase reactant and can become transiently elevated by infection, inflammation and trauma. PAI-1 levels increase during pregnancy. Since the PAI-1 antigen assay measures both functional and dysfunctional protein, it is of limited utility in the assessment of congenital PAI-1 deficiency.6

Methodology

Enzyme-linked immunosorbent assay (ELISA)

Footnotes

1. Adcock DM, Kressin DC, Marlar RA. Effect of 3.2% vs 3.8% Sodium Citrate Concentration on Routine Coagulation Testing. Am J Clin Pathol. 1997 Jan;107(1):105-110.8980376
2. Reneke J, Etzell J, Leslie S, Ng VL, Gottfried EL. Prolonged Prothrombin Time and Activated Partial Thromboplastin Time Due to Underfilled Specimen Tubes With 109 mmol/L (3.2%) Citrate Anticoagulant. Am J Clin Pathol. 1998 Jun;109(6):754-757.9620035
3. National Committee for Clinical Laboratory Standardization: Collection, Transport, and Processing of Blood Specimens for Coagulation Testing and General Performance of Coagulation Assays; Approved Guideline, Fifth Edition, Villanova: NCCLS Document H21-A5:28(5), 2008.
4. Gottfried EL, Adachi MM. Prothrombin Time and Activated Partial Thromboplastin Time Can Be Performed on the First Tube. Am J Clin Pathol. 1997 Jun;107(6):681-683.9169665
5. McGlasson DL, More L, Best HA, Norris WL, Doe RH, Ray H. Drawing Specimens for Coagulation Testing: Is a Second Tube Necessary? Clin Lab Sci. 1999 May-Jun;12(3):137-139.10539100
6. Mehta R, Shapiro AD. Plasminogen activator inhibitor type I deficiency. Haemophilia. 2008 Nov;14(6):1255-1260.19141166
7. Huber K, Christ G, Wojta J, Gulba D. Plasminogen activator inhibitor type-1 in cardiovascular disease. Status report 2001. Thromb Res. 2001 Sep 30;103 Suppl 1:S7-S19.11567664
8. Huber K. Plasminogen activator inhibitor type-1 (part one): basic mechanisms, regulation, and role for thromboembolic disease. J Thromb Thrombolysis. 2001 May;11(3):183-193.11577256
9. Huber K. Plasminogen activator inhibitor type-1 (part two): role for failure of thrombolytic therapy. PAI-1 resistance as a potential benefit for new fibronolytic agents. J Thromb Thrombolysis. 2001 May,11(3):195-202.11577257

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
146790 Plasminogen Act Inhibitor-1,Ag 22758-7 146791 Plasminogen Act Inhibitor-1,Ag ng/mL 22758-7

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