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Test ID: F_12 Coagulation Factor XII Activity Assay, Plasma

Reporting Name

Coag Factor XII Assay, P

Useful For

Diagnosing deficiency of coagulation factor XII


Determining cause of 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

Specimen Type: Platelet-poor plasma

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

Collection Container/Tube: Light-blue top (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 in Special Instructions.

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, ≤-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: 55-180%

Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥15% to 20%) which may not reach adult levels for ≥180 days postnatal.*

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

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_12 Coag Factor XII Assay, P 3232-6


Result ID Test Result Name Result LOINC Value
F_12 Coag Factor XII Assay, P 3232-6

Clinical Information

Factor XII is synthesized in the liver. Its biological half-life is 40 to 50 hours. Factor XII is a component of the contact activation system and is involved in both intrinsic pathway and fibrinolytic system.


Factor XII deficiency is often discovered when activated partial thromboplastin time is found to be unexpectedly long. The deficiency causes no known bleeding disorder.


An association between severe factor XII deficiency and thrombosis risk has been proposed, but not proven.


Acquired deficiency is associated with liver disease, nephritic syndrome, and chronic granulocytic leukemia.


Congenital homozygous deficiency: 20% activity


Congenital heterozygous deficiency: 20% to 50% activity

Clinical Reference

Renne T, Schmaier AH, Nickel KF, et al: In vivo roles of factor XII. Blood. 2012 Nov 22;120(22):4296-4303

Report Available

1 to 3 days

Method Name

Optical Clot-Based

Mayo Clinic Laboratories | Hematology Catalog Additional Information: