Sign in →

Test ID: F_9 Coagulation Factor IX Activity Assay, Plasma

Reporting Name

Coag Factor IX Assay, P

Useful For

Diagnosing deficiencies, particularly hemophilia B (Christmas disease)


Assessing the impact of liver disease on hemostasis


Investigation of a 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 (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

≤6 months: Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥20%) which may not reach adult levels for ≥180 days postnatal.* (Literature derived)

>6 months: 65-140%

*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_9 Coag Factor IX Assay, P 3187-2


Result ID Test Result Name Result LOINC Value
F_9 Coag Factor IX Assay, P 3187-2

Clinical Information

Factor IX is a vitamin K-dependent serine protease synthesized in the liver and participates in the intrinsic coagulation pathway. Its biological half-life is 18 to 24 hours.


Congenital deficiency inherited as an X-linked recessive bleeding disorder (hemophilia B). Severe deficiency (<1%) characterized by hemarthroses, deep tissue bleeding, excessive bleeding with trauma and ecchymoses.


Acquired deficiency associated with liver disease, vitamin K deficiency, warfarin therapy and inhibitors (rare).


Acquired deficiency is more common than congenital.


Mild hemophilia B: 5% to 50% activity


Moderate hemophilia B: 1% to 5% activity


Severe hemophilia B: <1% activity

Clinical Reference

1. Barrowcliffe TW, Raut S, Sands D, Hubbard AR: Coagulation and chromogenic assays of factor VIII activity: general aspects, standardization, and recommendations. Semin Thromb Hemost. 2002 Jun;28(3):247-256

2. Franchini M, Lippi G, Favaloro EJ: Acquired inhibitors of coagulation factors: part II. Semin Thromb Hemost. 2012 Jul;38(5):447-453

3. Carcao MD: The diagnosis and management of congenital hemophilia. Semin Thromb Hemost. 2012 Oct;38(7):727-734

Report Available

1 to 3 days

Testing Algorithm

For information see Hemophilia Testing Algorithm

Method Name

Optical Clot-Based

Mayo Clinic Laboratories | Hematology Catalog Additional Information: