Factor XI Activity Assay
General Information
Lab Name
Factor XI Activity
Lab Code
F11
Epic Name
Factor XI Activity
Description
Factor XI (11) activity is a PTT-based factor assay used for diagnosing deficiency of coagulation factor XI. A relatively high incidence of congenital factor XI deficiency (Hemophilia C) occurs among individuals of Ashkenazi Jewish descent.
Emicizumab (Hemlibra) will affect all PTT-based assays and will overestimate the factor concentrations.
Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Synonyms
Factor 11
Interpretation
Method
Stago STA Clottable Factor assay
Reference Range
Units: %
| Female | Male | ||
|---|---|---|---|
| Age | Range | Age | Range |
| 0-29d | 23-150 | 0-29d | 23-150 |
| 1m-2m | 27-150 | 1m-2m | 27-150 |
| 3m-5m | 41-150 | 3m-5m | 41-150 |
| 6m-11m | 38-150 | 6m-11m | 38-150 |
| 1y- | 50-150 | 1y- | 50-150 |
Effective date: 07/01/2004
Interferences and Limitations
Clinical assay interference and limitations: Patients on bivalirudin (Angiomax), dabigatran (Pradaxa), argatroban (Novastan), rivaroxaban (Xarelto), apixaban (Eliquis), and edoxaban (Savaysa) 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 concentrations.
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 Instructions: Take specimen to UW-MT Coag lab for processing. Coag Tech will freeze plasma sample for transport to HMC Coag.
HMC Instructions: Take specimen to HMC 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 |
|---|
Frequency
Run Monday-Friday. Reported by end of day.
Available STAT?
Yes, Monday to Friday 8 am - 3 pm. For other times contact the Lab Medicine resident for approval. Please notify the Special Coag lab on Friday (206-744-2621) if sending a stat factor XI on the weekend.
Billing & Coding
CPT codes
85270
LOINC
Interfaced Order Code
UOW1218
Interfaced Result Code
UOW1218