Test Name
ANTI-FACTOR Xa
Aliases
ANTI-XA ASSAY, FACTOR XA INHIBITION ASSAY, HEPARIN ANTI-XA ASSAY
Abbreviations
-
Test Classification
INDIVIDUAL
Department
HEMATOLOGY
Sub Department
COAGULATION
TAT Category
ELAPSED (CONTINUOUS) TIME
Estimated TAT
7
TAT Units
DAYS
Test Requirements
2mL frozen platelet poor citrated plasma.
SAMPLE COLLECTION & HANDLING
A. BLOOD COLLECTION
Fill tube completely (to ensure proper 9:1 blood-to-citrate ratio).
Gently invert 3-6 times (no vigorous shaking to prevent hemolysis).
For UFH monitoring: Draw sample at steady-state (usually 4–6 hours after IV infusion starts).
For LMWH monitoring: Draw peak level at 4 hours post-subcutaneous injection.
For DOACs (rivaroxaban/apixaban): Timing depends on purpose (peak: ~2–4 hrs post-dose; trough: just before next dose).
B. PROCESSING
Centrifuge promptly (within 1 hour of collection).
Separate plasma carefully (avoid platelet contamination).
Freeze plasma.
For instructions/ further guidance on how to prepare platelet poor plasma, please visit this YouTube video: https://www.youtube.com/watch?v=9z6c8Bgr2EY
Clinical Utility
"✅ GOLD STANDARD FOR HEPARIN MONITORING (UFH/LMWH).
✅ ESSENTIAL FOR DOACs IN BLEEDING/THROMBOSIS.
✅ SUPERIOR TO APTT IN COMPLEX PATIENTS (LUPUS, PREGNANCY, OBESITY).
❌ NOT FOR DABIGATRAN OR WARFARIN MONITORING."
Last Review
26th Feb 2026