Thrombin Time

Casandra

Casandra Test Code LC40058Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 015230CPT Code 85670

Also known as: Thrombin Clotting Time (TCT)

Clinical Use

Order Test

Use

Diagnose fibrinogen deficiency, both congenital and acquired;6 identify heparin contamination of samples and direct thrombin inhibitor therapy.

Special Instructions

If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Coagulation Collection Procedures should be referred to for detailed guidance. Patients should ideally not be on anticoagulant therapy before the test, and certain therapies like warfarin should be avoided prior to testing.

Limitations

Thrombin time will be extended when functional fibrinogen levels are below 100 mg/dL due to various congenital and acquired conditions. Thrombin inhibitors including heparin, argatroban, and hirudin will cause an extended thrombin time. Proper handling and processing of specimens are crucial to prevent false results, e.g., severe hemolysis, improper labeling, clotted specimen can lead to sample rejection.

Test Details

Methodology

Other

Biomarkers

LOINC Codes

Order Codes

3243-3

Result Codes

3243-3

Result Turnaround Time

2-3 days

Specimen

Plasma

Volume

1 mL

Minimum Volume

Not provided

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. Evacuated collection tubes must be filled to completion. Immediately mix by gentle inversion at least six times. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma with a plastic transfer pipette. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap. Freeze immediately and maintain frozen until tested.

Patient Preparation

Ideally the patient should not be on anticoagulant therapy. Avoid warfarin therapy for two weeks prior and heparin for three days prior to testing.

Storage Instructions

Freeze.

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.