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Test Code PTINR Prothrombin Time

Important Note

Specimen tube must be full. The ratio of blood to anticoagulant is critical. Incorrect blood to anticoagulant ratio will cause erroneous results.

Please indicate if patient is on anticoagulant therapy.

Specimen Requirements

Submit only one of the following specimens


Specimen Type:  Whole Blood
Container/Tube: Light Blue Top (3.2% Sodium Citrate)
Volume: 2.7mL Whole Blood (Tube must be full)
Collection Instructions: Send whole blood specimen to laboratory immediately.


Specimen Type: Platelet Poor Plasma
Container/Tube: Light Blue Top (3.2% Sodium Citrate)
Submission Container/Tube: Plastic Vial

Minimum Volume: 1.0mL Plasma
Collection Instructions:

1. Light Blue top tube must be properly filled with whole blood.

2. Whole blood specimen should be double centrifuged and plasma separated from cells within 4 hours of collection

3. Freeze the plasma in well-closed plastic tube immediately.

Reference Interval

Adults 9.7 – 11.8 seconds
Venous Thromboembolism 2.0 – 3.0 INR
Mechanical Heart Valves 2.5 - 3.5 INR

Call back values: Refer to Critical Values Table

Days and Times Performed

Monday through Sunday, TAT 1 day

Methodology

Photo-optical Clot Detection

Service Code

12403

Update

Last updated 02/05/2017

Unacceptable Condition

Haemolysis Gross reject
Icterus NA
Lipaemic NA
Others Clotted or insufficient reject

 

Specimen Stability

 **Preferred temperatures for storage prior to and during shipping to NUH** 

 

Specimen Type

Whole Blood

 Plasma
Ambient 24 hours 24 hours
Refrigerate Unacceptable Unacceptable
Frozen NA 14 days

 

Testing Laboratory

National University Hospital
Haematology, 67725320

Useful For

Monitoring of anticoagulation therapy, e.g. Warfarin.

Screening test for clotting factor deficiency, e.g. Factor VII.

PTINR will be prolonged in disseminated intravascular coagulation, liver disease and vitamin K deficiency.

Alias

PT
INR
Protime