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
Synonyms
Factor 9
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
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
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.
Performance
LIS Dept Code
Coagulation (COAG)
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, |
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.
Billing & Coding
CPT codes
85250
LOINC
Interfaced Order Code
UOW1152
Interfaced Result Code
UOW1152