Clinical relevance
Rivaroxaban is a direct inhibitor of activated factor X (FXa) and is given orally for the prophylaxis of a range of conditions including the prevention of stroke/systemic embolism in atrial fibrillation.
Edoxaban does not require routine anticoagulant monitoring but measurement would be required in certain clinical situations where the result will alter management, including prior to emergency surgery or when bleeding.
Reference range
Expected levels 3-hours post dose on patients taking ‘therapeutic’ doses of the drug:
Rivaroxaban 200 – 400 ng/mL
Clinicians should seek the advice of the on-call Haematologist if they are unsure on how to interpret the anti-XA activity results.
Minimum volume
The volume of blood in coagulation samples must lie within the volume range as indicated by the size of the black fill arrow present on tubes. Volumes above or below the arrow will result in sample rejection to ensure validity of results.
Turnaround time
4 hours
Age of sample
Samples will be rejected if received more than 1 hours post venepuncture.
Specimen requirements
- 2 blue top (sodium citrate) samples
- all coagulation tubes must be adequately filled (see above)
- All coagulation tubes must be mixed several times by gentle inversion immediately after venepuncture. Mixing the sample the anticoagulant stops the sample clotting within the tube.
Limitations
- It is not possible to provide results on clotted, insufficient, lipaeamic or haemolysed samples. These samples will be rejected with the appropriate comment.
- Samples tubes that have expired cannot be accepted
Analysing laboratory
Coagulation Lab, James Cook University Hospital, Marton Road, TS4 3BW