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Factor IX Activity

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Updated Test Information:

Test Description
Factor IX Activity
Synonym(s)

Factor 9, UOW1152
Test ID
F9
General Information

Factor IX (9) activity is a PTT-based factor assay used for diagnosing congenital factor IX deficiency (hemophilia B) and evaluating for acquired deficiencies associated with liver disease, vitamin K deficiency and factor IX inhibitors. Factor IX activity can also be used to monitor infusions of factor IX replacement therapy during procedures and prophylactic infusions.


Certain recombinant Factor IX formulations may give unreliable results with this assay, and chromogenic Factor IX activity assays should be used to monitor these patients.


Emicizumab (Hemlibra) will affect all PTT-based assays and will overestimate the factor concentration.
Container Type

3 mL or 5 mL Light Blue Citrate Tube
Specimen Type

Blood
Specimen Requirements

Entire Specimen
Specimen Collection / Processing Instructions

MUST PROCESS WITH 4 HOURS OF COLLECTION
Platelet poor Coag Citrate Specimen processing:
1. Gently invert tube 2-3 times prior to placing in Centrifuge
2. Centrifuge Citrate whole blood at 4500 rpm for 10 minutes
3. Carefully pipette plasma, avoiding the platelet/buffy coat into a plastic vial
4. Centrifuge plasma at 4500 rpm for 10 minutes
5. Pipette the plasma to a plastic vial, leaving the bottom 0.25 mL undisturbed
6. Freeze plasma immediately and transport frozen. 
Minimum Sample Volume

1 mL
Limitations

Patients on bivalirudin (Angiomax), dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa) and argatroban (Novastan) may show prolonged clotting times. This may cause an under-estimation of the factor concentrations.


Emicizumab (Hemlibra) will affect all PTT-based assays and will overestimate the factor concentration.


Certain recombinant Factor IX formulations may give unreliable results with this assay, and chromogenic Factor IX activity assays should be used to monitor these patients.


Elevated factor VIII (8) levels (>250%) will result in a false increase in factor IX, XI, and XII assays.
Department (code)

Coagulation (COAG)
Methodology

Stago STA Clottable Factor assays
Estimated TAT

Report by end of next business day
Testing Schedule

Monday - Friday
CPT Code(s)

85250
Reference Range

                                            Units: %
            Female                                                 Male
Age                Range                       Age                  Range
0-29d           15-150                    0-29d              15-150
1m-5m        21-150                   1m-5m             21-150
6m-11m     36-150                  6m-11m           36-150
1y-                 60-150                  1y-                       60-150
STAT Orderable (Y/N)

Yes
Performing Lab

UW
LOINC Code(s)
Collection File View/Download File