Preferred Sample Type

PT / INR and Partial Thromboplastin Time (PTT)

PT / INR and Partial Thromboplastin Time (PTT)

Specimen Volume

3.5 mL

Specimen Transport

Standard transport to laboratory

Sample Preparation

Samples for any coagulation tests must be filled to the black fill line indicated on the sample tube. Any sample filled above or below this level will be rejected and a repeat sample will be required

Turnaround Time

24 hours

Sample Processing In Laboratory

Sample should be centrifuged

Sample Stability

12 hours from venepuncture (ideally received no later than 4 hours after collection)

General Information

Samples that meet the following criteria will not be processed:

  • Haemolysed, clotted, underfilled or overfilled samples.
  • Samples >12 hours old from the time of collection.
  • Samples received from other hospital laboratories that have been frozen and thawed.
  • Samples which fail the minimum data set.

Assay Limitations:

  • PT/INR: results are not affected by heparin up to 1 U/ml, haemoglobin up to 500 mg/dl, triglycerides up to 1000 mg/dl or bilirubin up to 30 mg/dl.
  • APTT: results are not affected haemoglobin up to 500 mg/dl, triglycerides up to 1000 mg/dl or bilirubin up to 26 mg/dl.
  • For grossly lipaemic samples an alternative mechanical clot detection based assay is used for PT and APTT

Reference Range

Prothrombin Time ratio (PT) 0.8-1.2 (10-14.0 seconds)

INR Dependent upon therapeutic requirement

PTT Ratio 0.8-1.2 (23-34 seconds)

 

 

Specifications

  • EQA Status: NEQAS
  • EQAS Scheme: Yes

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