Laboratory Medicine Program

Prothrombin Time (PT/INR)
(PT, INR)

Clinical Decription:
The Prothrombin Time measures the clotting time of plasma indicating the overall efficiency of the extrinsic clotting system and concentrations of factors V, VII, X and Fibrinogen. The assay is reported as an INR (International Normalized Ratio) which enables standardization of warfarinized patients.

Method: Optical Clot Detection; Siemens Sysmex CS-5100

Component Tests Used: INR (International Normalized Ratio)

Reference Ranges Used:
Prothrombin time 10.3 - 14.8 sec | INR 0.9 - 1.2

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. 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

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For more information, call 416.340.5227 or 1.866.865.5227

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