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Test ID: CH9 Chromogenic Factor IX Activity Assay, Plasma

Ordering Guidance

Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, ALBLD / Bleeding Diathesis Profile, Limited, Plasma is recommended.

Necessary Information

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

Specimen Required

Specimen Type: Platelet-poor plasma

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

Submission Container/Tube: Polypropylene vial

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.

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

3. Aliquot plasma into a separate plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally at ≤-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.

Useful For

Monitoring coagulation factor replacement therapy of selected extended half-life coagulation factor replacements


Aiding in the diagnosis of hemophilia B using a 2-stage assay, especially when a 1-stage assay was normal

Testing Algorithm

This assay is indicated in situations where there is a clinical suspicion of hemophilia B diagnosis, when the 1-stage assay is normal. However, this assay is also recommended for accurate classification of hemophilia B.


See Hemophilia Testing Algorithm in Special Instructions

Reporting Name

Chromogenic FIX, P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Clinical Information

Factor IX (FIX) 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 FIX deficiency is 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.


Typically, these patients are tested using a 1-stage clotting assay. However, new treatment options using long-acting glycoPEGylated replacement products are being approved for clinical use. Pharmacokinetic studies for these products indicate ideal monitoring of patients should be performed by the 2-stage chromogenic assay.

Reference Values



Chromogenic Factor IX activity generally correlates with the one-stage FIX activity. In full term/premature neonates, infants, children, and adolescents the one-stage FIX activity* is similar to adults. However, no similar data for chromogenic FIX activity are available. (Appel JTH 2012; 10:2254)


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


Factor IX deficiency may be acquired (eg, vitamin K deficiency, warfarin anticoagulation effect, liver disease, or a consumptive coagulopathy) or congenital (hemophilia B).


Optimal laboratory monitoring of selected extended half-life factor IX replacement therapy (eg, glycoPEGylated factor FIX) may be achieved with the chromogenic factor IX assay. Elevated factor IX levels may be associated with acute or chronic inflammation, excess factor IX replacement therapy, or as a result of a rare genetic variant, factor IX Padua.

Clinical Reference

1. Bowyer AE, Hillarp A, Ezban M, et al: Measuring factor IX activity of noacog beta pegol with commercially available one-stage clotting and chromogenic assay kits: a two-center study. J Thromb Haemost 2016 Jul;14(7 1428-1435 doi: 10.1111/jth.13348

2. Kitchen S, Signer-Romero K, Key NS: Current laboratory practices in the diagnosis and management of haemophilia: a global assessment. Haemophilia 2015 Jul;21(4)550-557

3. Sorensen MH, Anderson S, Ezban M: Factor IX-deficient plasma spiked with N9-GP behaves similarly to N9-GP post-administration clinical samples in N9-GP ELISA and FIX activity assays. Haemophilia 2015 Nov;21(6):832-836

4. Dodt J, Hubbard AR, Wicks SJ, et al: Potency determination of factor VIII and factor IX for new product labelling and postinfusion testing: challenges for caregivers and regulators. Haemophilia 2015 Jul;21(4):543-549

5. Wilmot HV, Hogwood J, Gray E: Recombinant factor IX: discrepancies between one-stage clotting and chromogenic assays. Haemophilia 2014 Nov;20(6):891-897

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Test Classification

This test was developed, and its performance characteristics 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
CH9 Chromogenic FIX, P 88449-4


Result ID Test Result Name Result LOINC Value
CH9 Chromogenic FIX, P 88449-4

Method Name


Mayo Clinic Laboratories | Hematology Catalog Additional Information: