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Tissue Plasminogen Activator (tPA) Antigen

CPT 85415

Test Details

Methodology

Enzyme-linked immunosorbent assay (ELISA)

Result Turnaround Time

4 - 8 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

For more information, please view the literature below.

Procedures for Hemostasis and Thrombosis: A Clinical Test Compendium

Use

Quantitative determination of human tissue plasminogen activator antigen in plasma by enzyme immunoassay

Limitations

The tPA will most likely be increased with a difficult or traumatic venipuncture or if the tourniquet is left on too tight and/or too long.

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. 5th ed. Villanova, Pa: NCCLS; 2008. Document H21-A5:28(5).
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

References

Adcock DM, Bethel MA, Macy PA. Coagulation Handbook. Aurora, Colo: Esoterix−Colorado Coagulation; 2006.

Custom Additional Information

Tissue plasminogen activator is a major regulator in the fibrinolytic system and its physiologically serves to activate plasminogen to plasmin. Plasmin degrades fibrin to soluble fibrin degradation products. Fibrinolysis is regulated by specific molecular interactions between tPA and fibrin as well as between plasmin and the specific plasmin inhibitor, alpha-2 antiplasmin. Tissue plasminogen activator is stored in the endothelial cells and is rapidly released following exercise, venous occlusion, and injection of substances such as epinephrine and DDAVP. It is primarily inhibited by plasminogen activator inhibitor-1 (PAI-1). As the primary mediator of endogenous fibrinolysis, elevated tPA levels are strongly associated with preclinical atherosclerosis and have been shown to indicate risk of future myocardial infarction. In addition, healthy men participating in the Physician's Healthy Studies demonstrated that increased tPA levels are associated with increased risk of stroke. Individuals in the top 5% of values for tPA (>19.7 ng/mL) were four times more likely to experience a stroke than those with values below this cutoff level.

Specimen Requirements

Specimen

Plasma, frozen

Volume

1 mL

Container

Blue-top (sodium citrate) tube

Collection Instructions

Citrated plasma samples should be collected by double centrifugation. 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 except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.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. Serum gel tubes with clot initiators should also be collected after the citrate tubes. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma without disturbing the cells, using a plastic transfer pipette. Deliver to a plastic transfer 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 plastic lavender top tube with cap (Labcorp No. 49482). The specimen should be frozen immediately and maintained frozen until tested. To avoid delays in turnaround time when requesting multiple test on frozen samples, please submit separate frozen specimens for each test requested.

Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

Reference Range

<14.1 ng/mL

Storage Instructions

Freeze; six freeze/thaw cycles are acceptable.

Causes for Rejection

Hemolysis; specimen clotted with fibrin; specimen contaminated with heparin (ie, drawn with blood gases)

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
500029 Tissue Plasminogen Act. Ag. 500030 TPA Antigen ng/mL 5971-7
Order Code500029
Order Code NameTissue Plasminogen Act. Ag.
Order Loinc
Result Code500030
Result Code NameTPA Antigen
UofMng/mL
Result LOINC5971-7