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Factor IX Antigen
Test Code91053
CPT Codes
85250
Preferred Specimen
1 mL frozen platelet-poor plasma collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.5 mL
Instructions
Platelet-poor plasma: Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic screw-cap vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic screw-cap vial. Plasma must be free of platelets (<10, 000/mcl). Freeze immediately and ship on dry ice.
Transport Temperature
Frozen
Specimen Stability
Room temperature: 4 hours
Refrigerated: 48 hours
Frozen -20° C: 30 days
Frozen -70° C: 6 months
Refrigerated: 48 hours
Frozen -20° C: 30 days
Frozen -70° C: 6 months
Methodology
Immunoassay (IA)
Setup Schedule
Set up: As needed, at least 1x per month; Report available: 2-31 days
Clinical Significance
The laboratory diagnosis of factor IX deficiency typically involves quantitative determinations of functional activity of factor IX. An ELISA for factor IX antigen may be used in conjunction with functional assays in the area of gene therapy, assessment of factor IX concentrates, determination of carrier status as well as distinguishing those patients with cross-reactive material (i.e. low functional activity but near normal antigen levels of factor IX).
