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The euglobulin lysis time is a global nonspecific screen of the fibrinolytic system.
This is a semiquantitative assay. The diagnostic potential of euglobulin lysis times is limited by the extreme variation in lysis times among healthy individuals.6 Both hypofibrinogenemia and factor XIII deficiency may result in a shortened lysis time. In the case of hypofibrinogenemia, the shortened time is due to the decreased amount of fibrin to be lysed. In factor XIII deficiency, the clot is not stabilized by covalent cross-linking of fibers and can be readily lysed by plasmin. Traumatic venipuncture, prolonged stasis, or incorrect sample preparation may invalidate test results.
This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).
The euglobulin fraction of the plasma refers to plasma proteins that precipitate at low pH and decreased ionic strength.6 In the ELT test, plasma inhibitors of fibrinolysis are physically removed and the reaction of fibrinogen, plasminogen, and plasminogen activators are assayed. The precipitate also includes tissue plasminogen activators, plasminogen, plasmin, and fibrinogen. The inhibitors of lysis, α2-antiplasmin, and α2-macroglobulin, do not precipitate. In the test system, the euglobulin precipitate is redissolved in buffer, and clotting is initiated with calcium. The assay is performed in a microtiter plate. The time required for the intrinsic plasmin to lyse the fibrin clot equates to the euglobulin lysis time.
The euglobulin lysis time (ELT) test provides an overview of the fibrinolytic system function by measuring the time it takes for an in vitro clot to dissolve in the absence of plasmin inhibitors.6 The fibrinolytic system is initiated following activation of the contact factors in the coagulation cascade. Fibrinolytic system activation leads to the production of plasmin, a proteolytic enzyme capable of degrading fibrin and fibrinogen as well as other plasma proteins. Increased fibrinolytic activity is suggested by clot lysis that occurs in less than two hours. A shortened ELT result implies excessive fibrinolytic activity that may be primary or could be secondary to inflammation, malignancy, trauma, fracture, liver disease, or thrombolytic therapy. Clinical bleeding is a possible consequence of excessive fibrinolysis. Excessive fibrinolysis may result from increased levels of tissue plasminogen activator (TPA), increased plasmin activity, decreased levels of plasminogen activator inhibitor-1 (PAI-1), or decreased α2-antiplasmin activity. The effect of fibrinolysis is the production of plasma fibrin(ogen) degradation products (FDP or FSP) and D-dimer fragments. A prolonged ELT result implies a defect in the fibrinolytic system such as elevated plasminogen activator inhibitor (PAI-1) levels, elevated levels of α2-antiplasmin, a plasminogen deficiency, or decreased tissue plasminogen activator (TPA) activity. The ELT may also be prolonged if the fibrinogen level exceeds 600 mg/dL. Inadequate fibrinolysis may be associated with superficial or deep vein thrombosis, pulmonary embolism, coronary thrombosis, transient ischemic attack, or stroke.
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. 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 N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests 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.
Causes for Rejection
Severe hemolysis; improper labeling; clotted specimen; specimen diluted with IV fluids; samples thawed in transit; improper sample type; sample out of stability