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HelpTest Code IHA Factor VIII or Factor IX Inhibitor Assay
Laboratory Code
LAB1116 (FVIII)
LAB3040775 (FIX)
Specimen Requirements
Submit only one of the following specimens
Specimen Type: Whole Blood
Container/Tube: 3 Light Blue Top (3.2% Sodium Citrate)
Volume: 3 × 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: 3 Light Blue Top (3.2% Sodium Citrate)
Submission Container/Tube: Plastic Vial
Minimum Volume: 3.0 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 1.5 mL each.
4. Freeze the aliquots in well-closed plastic tubes immediately.
Specimen Stability
| Specimen Type | Plasma |
|---|---|
| Ambient | 4 hours |
| Refrigerate | 4 hours |
| Frozen | 14 days (preferred) |
Methodology
Photo-optical Clot Detection, Bethesda 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
< 0.5 Bethesda Unit
Testing Laboratory
National University Hospital
Haematology, 67725320
Useful For
Detecting the presence and titer of a specific factor inhibitor directed against coagulation Factor VIII or Factor IX.
Service Code
12413
LOINC Code Information
13591-3
Alias
Bethesda Assay
Factor VIII Inhibitor
Factor IX Inhibitor
Update
Last updated 20/03/2025