INR

Code:
INR-POC

Sample Type:

Fresh capillary blood

Ref Ranges/Units:

Measurable range: 0.8 – 8.0.

Results >5 should be repeated using a different finger.

Results >6 should be confirmed via laboratory venous sample.

Turnaround:

1 minute

Pathology

Special Precautions/Comments:

The first drop of blood must be applied to the test strip within 15 seconds

The presence of antiphospholipid antibodies (APA) may lead to falsely elevated INR results

Interactions between oral anticoagulants and other medications can lead to changes in INR results

Additional Information:

International Normalised Ratio (INR) measurement is used for monitoring Vitamin K antagonist anticoagulant therapy (primarliy Warfarin). The patients Prothrombin Time (PT) is divided by the laboratory Mean Normal Prothrombin Time (MNPT) and the resulting ratio is then raised to the power of the ISI, to convert results to a common WHO standard.

Interferences:

There is no significant effect on test results from the following:

  • Bilirubin up to 513 µmol/L
  • Haemolysis up to 1000 mg/dL
  • Haematocrit between 15 – 55%
  • Triglycerides up to 11.4 mmol/L
  • Ascorbic acid up to 50 mg/L
  • Unfractionated heparin (uFH) / low molecular weight heparin (LMWH) up to 3 IU/mL

 

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