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.
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
References
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 Code | 500029 | |||||
Order Code Name | Tissue Plasminogen Act. Ag. | |||||
Order Loinc | ||||||
Result Code | 500030 | |||||
Result Code Name | TPA Antigen | |||||
UofM | ng/mL | |||||
Result LOINC | 5971-7 |