International Normalized Ratio (INR) Test

Synonyms

international normalized ratio

Purpose

The INR Test is a type of calculation based on prothrombin test results. It is used to monitor wafarin anticoagulant therapy.

Patient Preparation

The patient may need to delay the daily dose of warfarin.

Samples

2.7ml or 1.8ml sized tube filled to 90% capacity, with a minimum volume of90% of full draw whole blood or plasma collected in a blue top tube(sodium citrate). Evacuated collection tubes must be filled to completion and mixed immediately by inversion to ensure a proper blood to anticoagulant ratio. Store sample at room temperature up to 24hours, after which the sample is centrifuged and plasma frozen until ready for use.

Reference Range

0-1 month: 0.9 -1.4,>1 month: 0.9-1.2

Results Turnaround

Within 24 hours of receipt of samples.

Diseases / Diagnostic indicators

Too low INR levels indicate risk for blood clots while too high levels indicate risk for dangerous bleeding as in the case of haemophilia.