Test Catalog

Test Id : PAI1

Plasminogen Activator Inhibitor Antigen, Plasma

Useful For
Suggests clinical disorders or settings where the test may be helpful

Identification of heredity elevation or deficiency of plasminogen activator inhibitor type 1


Determination of risk for veno-occlusive disease associated with bone marrow transplantation


Differential diagnosis of impaired fibrinolysis


Prognostic marker of occurrence or recurrence of thrombosis

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Enzyme-Linked Immunosorbent Assay (ELISA)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

PAI-1 Ag, P

Lists additional common names for a test, as an aid in searching

PAI-1 Ag

Specimen Type
Describes the specimen type validated for testing

Plasma Na Cit

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (citrate)

Submission Container/Tube: Plastic vial (polypropylene preferred)

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.
2. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
3. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.
4. Freeze plasma immediately (no longer than 4 hours after collection) at -20 degrees C or, ideally below -40 degrees C.

Specimen Stability Information: Frozen 2 years

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.

Special Instructions
Library of PDFs including pertinent information and forms related to the test


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.

0.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen

Useful For
Suggests clinical disorders or settings where the test may be helpful

Identification of heredity elevation or deficiency of plasminogen activator inhibitor type 1


Determination of risk for veno-occlusive disease associated with bone marrow transplantation


Differential diagnosis of impaired fibrinolysis


Prognostic marker of occurrence or recurrence of thrombosis

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Plasminogen activator inhibitor type 1 (PAI-1) antigen is a single-chain glycoprotein (molecular weight 43 kDa) produced by endothelial cells and hepatocytes and is also present in alpha granules of platelets. PAI-1 is a serine protein inhibitor that is secreted in response to inflammatory reactions. Platelet alpha granules contain large amounts of PAI-1, which is released during vascular injury and assists in fibrin clot stability. PAI-1 is synthesized in the active form but has marked functional instability and a functional half-life of about 2 hours in vivo. Circulating PAI-1 is bound to vitronectin, which protects the inhibitor from inactivation and may assist in targeting the inhibitor to sites of vascular injury. At least 4 different conformations of PAI-1 have been described

1) The active form that reacts with plasminogen activator

2) A latent form that is nonreactive

3) A substrate form that can be cleaved by plasminogen activators but is noninhibitory

4) The inert form of PAI-1 generated by the cleavage of the reactive site


PAI-1 is the main inhibitor of tissue-type plasminogen activator (tPA) and urokinase plasminogen activator (uPA) and, as such, plays an important role in the regulation of fibrinolysis. Elevated levels of PAI-1 result in deficient plasminogen activation and are associated with a predisposition to thrombosis, including veno-occlusive disease (VOD) after bone marrow transplantation (BMT).


Primary injury to the hepatic sinusoidal endothelium and hepatocytes induced by high-dose chemoradiotherapy is believed to be the key event in the pathogenesis of VOD. The clinical diagnosis of VOD is complex because the clinical signs and symptoms can occur as a result of other processes that can complicate the posttransplant period such as sepsis, graft-versus-host disease (GVHD), cyclosporine toxicity, other medications, hemolysis, or parenteral nutrition. Liver biopsy, although safer since the widespread introduction of transjugular procedures, remains hazardous in this thrombocytopenic population. A sensitive and specific assay would be invaluable in guiding management and avoiding potentially hazardous invasive diagnostic procedures. Along these lines several investigators have studied various markers of hypercoagulability for possible pathogenic and predictive relevance. Aside from serum bilirubin level, no laboratory marker has been standardized as a diagnostic marker of VOD and the severity of VOD remains retrospectively defined. Lee et al analyzed 115 patients after allogenic BMT in an attempt to identify diagnostic and severity markers of VOD. Of the 115 patients, 50 developed VOD.(1) Multiple logistic regression models were constructed that included recognized relevant clinical and hemostatic variables. Of the hemostatic variables, only PAI-1 antigen was identified as an independent marker for the occurrence of VOD. This confirmed the findings of a previous, smaller study that PAI-1 is a powerful diagnostic marker of VOD during the early period post-BMT and can distinguish VOD from other causes of hyperbilirubinemia post-BMT, such as GVHD and drug toxicity. Furthermore, PAI-1 antigen and bilirubin were independent variables for predicting severe VOD.


Familial thrombosis has been associated with inherited elevation of plasma PAI-1 activity. Increased levels of PAI-1 have also been reported in many conditions including malignancy, liver disease, the postoperative period, septic shock, the second and third trimesters of pregnancy, obesity, and coronary heart disease.


Low plasma levels of the active form of PAI-1 have been associated with abnormal, clinically significant bleeding. Complete deficiency of PAI-1, either congenital or acquired, is associated with bleeding manifestations that include hemarthroses, hematomas, menorrhagia, easy bruising, and postoperative hemorrhage.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

3.0-72.0 ng/mL

Provides information to assist in interpretation of the test results

Increased levels of plasminogen activator inhibitor type 1 (PAI-1) are associated with a predisposition to thrombosis.


Decreased or absent levels of detectable functional PAI-1 will result in a life-long bleeding diathesis.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The plasminogen activator inhibitor type 1 (PAI-1) level shows a diurnal variation with the highest levels occurring in the morning.


The PAI-1 level increases during pregnancy and decreases rapidly after delivery.


The extremely rare presence of antimouse antibodies in certain patients may lead to anomalous results.


Inappropriate specimen collection and processing may lead to platelet activation and release of platelet PAI-1. Consequently, care must be taken to remove all platelets and minimize platelet activation during specimen collection and processing.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Lee JH, Lee KH, Lee JH, et al: Plasminogen activator inhibitor-1 is an independent diagnostic marker as well as severity predictor of hepatic veno-occlusive disease after allogeneic bone marrow transplantation in adults conditioned with busulphan and cyclophosphamide. Br J Haematol. 2002 Sep;118(4):1087-1094

2. Stiko A, Hervio L, Loskutoff DJ: Plasminogen activator inhibitors. In: Colman RW, Hirsh J, Marder VJ, et al, eds. Hemostasis and Thrombosis. Lippincott; 2001:355-365

3. Vaughn DE, Declerck PJ: Regulation of fibrinolysis. In: Loscalzo J, Schager A, eds. Thrombosis and Hemorrhage. Lippincott; 2003:389-396

4. Goodnight SH Jr, Hathaway WE: Fibrinolytic defects and thrombosis. In: Disorders of Hemostasis and Thrombosis: A Clinical Guide. McGraw-Hill Book Company; 2001:389-396

5. Kruithof EK, Gudinchet A, Bachman F: Plasminogen activator inhibitor-1 and plasminogen activator inhibitor-2 in various disease states. Thromb Haemostasis. 1988;59(1):7-12

6. Salat C, Holler E, Kolb HJ, et al: Plasminogen activator inhibitor-1 confirms the diagnosis of hepatic veno-occlusive disease in patients with hyperbilirubinemia after bone marrow transplantation. Blood. 1997;89:2184-2188

7. Fay WP, Shapiro AD, Shih JL, Schleef RR, Ginsburg D: Brief report: complete deficiency of plasminogen-activator inhibitor Type 1 due to a frame-shift mutation. N Engl J Med. 1992 Dec 10;327(24):1729-1733

8. Heiman M, Gupta S, Khan SS, et al: Complete plasminogen activator inhibitor 1 deficiency. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews [Internet]; 2017 Accessed July 7, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK447152/

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Testing is performed on the Janus G3 liquid handler and BioTek microplate reader with Gen5 software using the Diagnostica Stago, Inc. Asserachrom PAI-1 kit. The method used is an enzyme-linked immunosorbent assay (ELISA). Microtiter plate wells are coated with mouse monoclonal antihuman PAI-1 antibody, which captures the PAI-1 in the sample. Next, a second antibody (mouse monoclonal antihuman PAI-1) coupled with peroxidase binds to another antigenic site distant from the first antibody, forming the "sandwich.'' The bound enzyme peroxidase is then visualized based on its ability to produce a color reaction when exposed to ortho-phenylenediamine and hydrogen peroxide. The reaction is stopped by the addition of a strong acid (1N HCl). The intensity of the color produced is directly proportional to the PAI-1 concentration in the plasma sample.(Package insert: ASSERACHROM PAI-1. Diagnostica Stago S.A.S; 03/2015)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.


Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

7 to 12 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
PAI1 PAI-1 Ag, P 22758-7
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
86083 PAI-1 Ag, P 22758-7

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports