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Test Code 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


 



Specimen Required


Specimen Type: Platelet-poor plasma

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

Submission Container/Tube: Polypropylene vial preferred

Specimen Volume: 1 mL

Collection Instructions:

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

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 or below.

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.


Secondary ID

65029

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.

 

For more information see Hemophilia Testing Algorithm.

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

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

65-140%

 

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 IM, Grimminck B, Geerts J, Stigter R, Cnossen MH, Beishuizen A. Age dependency of coagulation parameters during childhood and puberty. J Thromb Haemost. 2012;10(11):2254-2263)

 

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

Method Description

The chromogenic factor IX assay is performed on the Instrumentation Laboratory ACL TOP Family using the Rossix ROX Factor IX kit. In this 2-stage assay, patient plasma is diluted and combined with reagents containing factors VIII, X, V, XIa, and II, fibrin inhibitor, calcium chloride, and phospholipids. The factor IX in the patient's plasma is activated to IXa, which then aids in the activation of factor X to factor Xa. After a specified incubation period, chromogenic substrate is added at which time, the factor Xa, present from the previous step, hydrolyzes the substrate into peptide and p-nitroaniline (pNA). The color produced by the release of pNA is measured photometrically at 405 nm and is proportional to the factor IX in the sample.(Package insert: ROX FACTOR IX kit. Rossix AB, Molndal, Sweden, Rev 04/2014)

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

85130

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

Chromogenic