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HelpTest Code FXI Factor XI Assay
Laboratory Code
LAB309
Specimen Requirements
Submit only one of the following specimens
Specimen Type: Whole Blood
Container/Tube: 2 Light Blue Top (3.2% Sodium Citrate)
Volume: 2 × 2.7 mL whole blood (Tubes must be full)
Collection Instructions: Send whole blood specimens to laboratory immediately.
Specimen Type: Platelet Poor Plasma
Container/Tube: 2 Light Blue Top (3.2% Sodium Citrate)
Submission Container/Tube: Plastic Vial
Minimum Volume: 1.0 mL plasma
Collection Instructions:
1. Light blue top tube must be properly filled with whole blood.
2. Whole blood specimen should be double centrifuged and plasma separated from cells within 1 hr of collection.
3. Plasma should be separated into 2 aliquots with minimum volume of 1.0 mL each.
4. Freeze the aliquots in well-closed plastic tubes immediately.
Specimen Stability
| Specimen Type | Plasma |
|---|---|
| Ambient | 4 hours |
| Refrigerate | Not available |
| Frozen | 14 days (preferred) |
Panel Information
Panel includes the following tests:
- Activated Partial Thromboplastin Time
- Prothrombin Time
- Factor XI Activity Level
Methodology
Activated Partial Thromboplastin Clot-Based Assay
Days and Times Performed
Tuesday through Friday, TAT 14 days
Specimen Condition
| Haemolysis | Gross reject |
|---|---|
| Icterus | Gross reject |
| Lipaemia | Gross reject |
| Others | Clotted or insufficient reject |
Reference Interval
64 – 155 %
Testing Laboratory
National University Hospital
Haematology, 67725320
Service Code
12503
LOINC Code Information
| APTT | 14979-9 |
|---|---|
| FACTOR XI | 3226-8 |
| APPT (1+1) CORRECTION | 5946-9 |
| CONTROL PLASMA | 13488-2 |
Alias
Factor XI Activity
Update
Last updated 21/03/2025
Reflex Tests
- APTT mixing study if APTT is > 37.0 seconds