Factor 11 activity

Alphabetical Test listing

Factor 11 activity-13369

Test name:

Factor 11 activity

Test number:

13369

Excellian order number:

LAB13369

Abbreviation:

F11

Alternate names:

Antihemophilic factor C
Factor XI activity
Plasma thromboplastin antecedent (PTA)

Useful for:

To evaluate isolated APTT prolongation and to document specific factor XI deficiency

Patient preparation information:

Ideally, the patient should not be on anticoagulant therapy
Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing

Specimen type:

Sodium citrate (Na cit) plasma

Collection container:

Lt blue Sodium citrate (NaCit)

Volume:

1.0 mL

Collection instructions:

Do not draw from an arm with a heparin lock or heparinized catheter
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, to ensure adequate mixing of the anticoagulant with the blood
A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system
- With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube
When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes.
- Any tube containing an alternative anticoagulant should be collected after the blue-top tube
- Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted

Processing instructions:

Spin within two (2) hours of sample collection
Transfer plasma to a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as Na cit plasma
Freeze

Transport container:

Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)

Transport and stability:

Frozen - 28 days

Freeze/thaw cycles - stable x3

Reason for rejection:

Severe hemolysis
Improper labeling
Clotted specimen
Specimen diluted with I.V. fluids
Samples thawed in transit
Improper sample type
Sample out of stability

Performing lab:

LabCorp Burlington (086314): R-LC

Days set up:

Daily

TAT:

2 - 3 days

Method:

Factor XI activity is determined utilizing an aPTT-based one-stage clotting time assay. Factor XI-depleted plasma is used as the substrate and the clotting time with the patient plasma is compared to the clotting time of normal pooled plasma.

Reference ranges:

60 - 150%

CPT codes:

85270

LOINC code:

Result 3226-8

Date created:

03/29/2019

Revised date:

05/31/2024

Review date:

12/29/2023