Ecarin Clotting Time (ECT)

CPT: 85635
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Test Details

Use

Measure the activity of direct thrombin inhibitors in plasma

Limitations

Results of this test are for research purposes only by the assay's manufacturer. The performance characteristics of this assay have not been established. The result should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.

Methodology

Clotting time assay

Additional Information

The ecarin clotting time is prolonged in the presence of direct thrombin inhibitors such as hirudin and argatroban. The result is also prolonged in cases of hypofibrinogenemia (<50 mg/dL) and dysfibrinogenemia. Monitoring of hirudin dose is critical as there is no known antidote and severe bleeding may occur with overdose. ECT is not prolonged by the presence of a lupus anticoagulant and is not prolonged in patients on vitamin K antagonist therapy.

Specimen Requirements

Specimen

Plasma, frozen

Volume

1 mL

Minimum Volume

0.3 mL

Container

Blue-top (sodium citrate) tube

Patient Preparation

Do not draw from an arm with a heparin lock or heparinized catheter.

Collection

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.

Storage Instructions

Freeze; three freeze/thaw cycles are acceptable. Stable at room temperature for four hours.

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

Clinical Information

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

Griessbach U, Stürzebecher J, Markwardt F. Assay of hirudin in plasma using a chromogenic thrombin substrate. Thromb Res. 1985 Jan 15; 37(2):347-350. 3975877
Nowak G. The ecarin clotting time, a universal method to quantify direct thrombin inhibitors. Pathophysiol Haemost Thromb. 2003 Jul-2004 Aug; 33(4):173-183. 15583446

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
500190 Ecarin Clotting Time 500191 Ecarin Clotting Time sec 60242-5
500190 Ecarin Clotting Time 500969 Ecarin Clotting Time N/A

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