Factor IX Activity
Also known as: Antihemophilic Factor B
Use
Evaluate an isolated, prolonged aPTT and to document specific factor IX deficiency6-9
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions. Specimen should be frozen and transported with care to maintain integrity. Ensure the collection is from a site free of anticoagulants.
Limitations
Direct Xa or thrombin inhibitor therapy may cause artificially low results. Severe liver disease and vitamin K deficiency can reduce factor IX levels, affecting test accuracy in diagnosing hemophilia. Factor IX levels are not suitable for determining female carrier status, for which genetic testing is advised. Factor IX inhibitors can lead to falsely low levels. These inhibitors can develop following replacement therapy or spontaneously, particularly in individuals with autoimmune disorders.
Methodology
Other
Biomarkers
LOINC Codes
- 3187-2
- 3187-2
Result Turnaround Time
2-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
Not provided
Container
Blue-top (sodium citrate) tube
Collection Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio. The sample should be mixed immediately by gentle inversion at least six times. Use a discard tube if using a winged collection system to prevent under-filling.
Patient Preparation
Ideally, the patient should not be on anticoagulant therapy. Avoid warfarin (Coumadin®) for two weeks prior and heparin, direct Xa, and thrombin inhibitors for about three days prior. Do not draw from an arm with a heparin lock or heparinized catheter.
Storage Instructions
Freeze.
Causes for Rejection
Severe hemolysis; improper labeling; clotted specimen; specimen diluted with IV fluids; samples thawed in transit; improper sample type; sample out of stability
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 28 days |
Other tests from different labs that may be relevant