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Lab Dept:


Test Name:


General Information

Lab Order Codes:



Plasminogen Activator Inhibitor 1 Activity; PAI-1 Antigen

CPT Codes:

83520 – Immunoassay for analyte other than infectious agent antibody or infectious agent antigen; quantitative, not otherwise specified

Test Includes:

Plasminogen Activator Inhibitor 1 antigen level reported in ng/mL.


Test Indications:

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.

Lab Testing Section:

Coagulation - Sendouts

Referred to:

Mayo Medical Laboratories (MML: PAI1)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

7 – 12 days, testing performed once weekly on Thursday.

Special Instructions:

See Patient Preparation. PAI-1 has a circadian rhythm, high in the early morning and falling in the afternoon and evening. This change should be considered when planning PAI-1 plasma studies. The PAI-1 antigen reference range is based on fasting morning samples in adults.


Specimen Type:

Whole blood


Light Blue (Buffered Na Citrate 3.2 %) top tube

Draw Volume:

2.7 mL blood in a 3 mL tube (Minimum:1.8 mL in a 2 mL tube)

Processed Volume:

1 mL (Minimum: 0.3 mL) plasma


Routine venipuncture. Do Not use the first 2 mL of blood collected.

If the patient’s hematocrit is >55%, contact laboratory to obtain a special tube. Mix thoroughly by gentle inversion.

Special Processing:

Lab Staff:
PAI-1 is unstable and must be processed and frozen within 3 hours of specimen collection.

Double spin required: Centrifuge specimen for 5 minutes, aliquot/transfer plasma to a plastic tube. Spin plasma again for 5 minutes. Remove plasma to another plastic vial and freeze specimen immediately at < or = -40 degrees C. Forward promptly.

Note: Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results. Each coagulation assay requested, must have its own vial.

Patient Preparation:

It is recommended, but not required that specimen should be early morning fasting specimen (before 10 am).

Sample Rejection:

Improper tube; clotted samples; overfilled tubes; underfilled tubes; mislabeled or unlabeled specimens


Reference Range:

3 - 72 ng/mL

Note: Based on fasting and early morning collections in adults.

Critical Values:



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 anti-mouse 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.


Enzyme-Linked Immunosorbent Assay (ELISA)


Mayo Medical Laboratories August 2015

Harmening DH (1997) Clinical Hematology and Fundamentals of Hemostasis


2/1/2008: Method change, units change. Now performed at Fairview, previously forward to SE Blood Center of Wisconsin.
5/24/2010: Tubing of patient specimens is no longer prohibited.
2/16/2012: Fairview now forwards test to Blood Center of Wisconsin.
4/12/2012: Test moved from Fairview forward to Blood Center of Wisconsin to Mayo Medical Laboratories.

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