Laboratory Medicine Program

Thrombin Time

Clinical Decription:
A prolonged thrombin time suggests an anti-thrombotic effect. Correction with an anti-heparin agent such as protamine sulfate confirms heparin-like activity. The thrombin time with protamine sulfate, will correct shorter than normal range when the prolongation is due to heparin. Thrombin times which do not correct may be due to fibrin degradation products, dysfibrinogens or anti-bovine thrombin antibodies. Anti-bovine thrombin antibodies will mimic heparin in the TT. A chromogenic heparin anti-Xa will be negative or 0.00 IU/mL. The antibody is confirmed when human thrombin is substituted for the bovine thrombin and the TT becomes normal.
<br/><em>Peden JC, Bucher G. Blood coagulation, hemorrhage and thrombosis. ed. Tocantins LM, p. 333, 1964.</em>

Method: Optical Clot Detection; Siemens Sysmex CS-5100

Component Tests Used: n/a

Reference Ranges Used:
14.0 - 21.0 sec

Specimen Type: Citrated plasma
Collected In: 3.2% Sodium Citrate
Volume: 1.0 mL (minimum: 1.0 mL)

Shipping: Send frozen on dry ice.

Special Instructions: Patient should be fasting, if possible. Anticoagulants should be held for a requisite amount of time prior to testing to ensure no anticoagulant effect on the plasma. The specimen must be double-centrifuged to obtain a platelet-poor plasma specimen (Plt <10x10E9/L): 1. Immediately centrifuge specimen at 1500xG for 10 minutes. 2. Separate the plasma from the platelet/buffy coat and transfer into a clean plastic tube. 3. Centrifuge the separated plasma at 1500xG for 10 minutes. 4. Transfer 1.0 to 2.0 mL of the double-centrifuged plasma into a clean plastic tube, leaving approx. 200 uL for discard. 5. Freeze plasma aliquot immediately for storage. Maintain frozen for shipping and handling.

Testing Schedule(s): Daily.

Turnaround Time: 1 day

For more information, call 416.340.5227 or 1.866.865.5227