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Test ID: F_11 Coagulation Factor XI Activity Assay, Plasma

Reporting Name

Coag Factor XI Assay, P

Useful For

Diagnosing deficiency of coagulation factor XI


Investigating prolonged activated partial thromboplastin time

Specimen Type

Plasma Na Cit

Ordering Guidance

Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, we suggest ordering Coagulation Consultations.

Necessary Information

If priority specimen, mark request form, give reason, and request a call-back.

Specimen Required

Patient Preparation: Patient must not be receiving Coumadin or heparin therapy.

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Specimen must be collected prior to factor replacement therapy.

2. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.

3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

4. Aliquot plasma into a plastic vial, leaving 0.25 mL in the bottom of centrifuged vial.

5. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, less than or equal to -40° C.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reference Values

Adults: 55-150%

Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥10%) which may not reach adult levels for ≥180 days postnatal.*

*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing.

Day(s) Performed

Monday through Saturday

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
F_11 Coag Factor XI Assay, P 3226-8


Result ID Test Result Name Result LOINC Value
F_11 Coag Factor XI Assay, P 3226-8

Clinical Information

Factor XI is synthesized in the liver. Its biological half-life is 60 to 80 hours. Factor XI is a component of intrinsic coagulation pathway which, when activated, activates factor IX to IXa.


Factor XI deficiency may cause prolonged partial thromboplastin time. Deficiency associated with mild bleeding diathesis, but there is poor correlation between activity level and clinical bleeding. A relatively high incidence of congenital deficiency occurs among Ashkenazi Jewish descent (hemophilia C).


Acquired deficiency is associated with liver disease and rarely inhibitors.


Patients that are homozygous: <20% activity


Patients that are heterozygous: 20% to 60% activity

Clinical Reference

1. He R, Chen D, He S: Factor XI: hemostasis, thrombosis, and antithrombosis. Thromb Res. 2012 May;129(5):541-550

2. Martin-Salces M, Jimenez-Yuste V, Alvarez MT, Quintana M, Hernandez-Navarro F: Review: Factor XI deficiency: review and management in pregnant women. Clin Appl Thromb Hemost. 2010;16(2):209-213

3. Seligsohn U: Factor XI in haemostasis and thrombosis: past, present and future. Thromb Haemost. 2007 Jul;98(1):84-89

4. Santoro R, Prejano S, Iannaccaro P: Factor XI deficiency: a description of 34 cases and literature review. Blood Coagul Fibrinolysis. 2011 Jul;22(5):431-435

Report Available

1 to 3 days

Method Name

Optical Clot-Based

Mayo Clinic Laboratories | Hematology Catalog Additional Information: