Factor IX Activity

General Information

Lab Name: Factor IX Activity
Lab Code: F9
Epic Name: Factor IX Activity
Description: 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.

Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Forms & Requisitions: Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Synonyms: Factor 9
Components

Interpretation

Method

Stago STA Clottable Factor assay (PTT-based)

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

Effective date: 07/01/2004

Interferences and 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.

Ordering & Collection

Specimen Type: Blood
Collection: 3 or 5 mL BLUE TOP (CITRATE) tube
Forms & Requisitions: Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Handling Instructions: The Laboratory MUST process specimen within 4 hrs of blood collection.
Quantity: Requested: entire specimen

Processing

Receiving Instructions: UW-MT and HMC: Take specimen to Coag lab for processing.

Outside Laboratory: Centrifuge for 10 minutes, remove plasma & re-spin plasma for another 10 minutes. Decant & freeze plasma (minimum 1.0 mL) @ -20°C to -80°C. Send frozen on dry ice.

Misc Sendout

Performance

Lab Department

Coagulation(COAG)

Frequency

Monday-Friday ( 8 am-3pm). Result end of day.

Available STAT?

Yes, Monday-Friday 8am-3pm. For other times, contact Lab Medicine Resident (LMR) for approval. If approved for after hours or weekend stat testing, LMR will notify UW-ML Coag lab at 206-598-6242 for samples collected at UW-ML and HMC Coag Lab at 206-744-3128 for samples collected at HMC and outside locations.

Performing Location(s)

HMC	Coagulation 206-520-4600 325 9th Ave, Rm # GWH-47, Seattle, WA 98104-2420
UW-MT	Coagulation 206-520-4600 Clinical Lab, Room NW220, University of Washington Medical Center, 1959 NE Pacific street, Seattle, WA 98195

Billing & Coding

CPT Codes: 85250
LOINC: 3187-2
Interfaced Order Code: UOW1152
Interfaced Result Code: UOW1152