Biochemistry
Haematology and Transfusion
Clinical Microbiology (Including Virology)
Cellular Pathology
General Information
Immunology
Molecular Pathology
Preferred Sample Type
Anti-Xa Assay
Specimen Volume
3.5 mLSpecimen Transport
Standard transport to laboratory - State for the attention of Special Coagulation on request formSample Preparation
Turnaround Time
7 days (Unless urgent by prior arrangement with laboratory)Sample Processing In Laboratory
Sample should be centrifugedSample Stability
12 hours from venepuncture (ideally received no later than 4 hours after collection)General Information
Note: For external requests please click Here for Coagulation Disorders request form. Please complete all information fully
For urgent special coagulation assay information click Here
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:
- For accurate results samples should be collected 3-4 hours post dose, when the concentration in the blood is expected to be at peak level.
- Random and trough anti-Xa tests may also be requested when there are concerns that the anticoagulant may be accumulating e.g. in renal failure.
- If heparin is being given by continuous venous infusion, samples can be taken at any time but they must be taken from the other arm.
Notes
Please state anticoagulant on request form e.g. Apixaban, Fondaparinux, Rivaroxaban, LMWH, UFH. Samples must be collected 4 hours post dose.
LMWH: Samples should be taken 4 hours after subcutaneous injection, once steady state has been achieved after administration of at least three doses.
Reference Range
LMWH:
Prophylactic Reference Range 0.1-0.3 IU/mL
Therapeutic Range 0.5-1.0 IU/mL
Therapeutic range for mechanical heart valve during pregnancy 1.0-1.4 IU/mL
Rivaroxaban:
Stroke prevention in NVAF 20mg OD 184-343ng/mL[1]
Treatment of PE/DVT 20mg OD 189-419ng/mL[1]
Treatment of PE/DVT 10mg OD 7-273ng/mL[2]
Treatment of ACS 2.5mg OD 13-123ng/mL[2]
Apixaban:
Stroke prevention in NVAF 5mg BD 91-321ng/mL[1]
Stroke prevention in NVAF 2.5mg BD 69-221ng/mL[2]
Treatment of PE/DVT 10mg BD 111-572ng/mL[2]
Treatment of PE/DVT 5mg BD 59-302ng/mL[1]
Treatment of PE/DVT 2.5mg BD 30-153ng/mL[2]
Fondaparinux:
2.5mg OD 0.39-0.50ug/mL[1]
7.5mg OD 1.20-1.26ug/ml[1]
[1] Measurement of heparin, direct oral anti-coagulants and other non-coumarin anti-coagulants and their effects on haemostasis assays: A British Society for Haematology Guideline, Baker et al, Brit J Haematol, 2024
[2] Update of the International Council for Standardization in Haematology Recommendations for Laboratory Measurement of Direct Oral Anticoagulant, Douxfils et al, Thromb Haemost, 2021
Specifications
- EQA Status: NEQAS / ECAT
- EQAS Scheme: Yes